The most unique feature of the Wikipedia is its method of growth: any user on the Internet, including you, can add material to the Wikipedia, using a web technology known as a wiki.

The origin of that term, wiki, is from the Hawaiian word which means fast or quick. Its intention is to convey that this type of online data can be edited quickly. There are many websites which now use the wiki format in place of a forum.

It may sound like Wikipedia would get trashed by a lot of false information. The theory is that so many people view and edit the articles, that people with expertise immediately correct any misinformation. However, there certainly has been an ongoing problem with articles written about people, where political and personal views can skew the tone of the article or prompt people to vandalize the article with misinformation. As a result, articles about living persons are probably the least accurate topics on the Wikipedia.

The Wikipedia has a backbone of standard encyclopedic data, with scientific articles about plants and animals and the usual things you’d find in an encyclopedia. It also has almanac-type information, so it is a good place to look up things like geographic names and places. For example, practically every community and municipality in the US has an entry. Typically, a resident of the community will expand the article beyond the normal census data.

It is no surprise that the Wikipedia attracts a lot of contributors from the technology, scientific, and mathematics fields, which makes it a good place to read about those topics.

It is important to know that the Wikipedia, by its nature, is not considered to be a citable source for academic research. In other words, it’s a good place to read about something, to learn about something, to find an answer to a question, but it is not acceptable in legitimate research to cite it as a reference. However, most articles in Wikipedia cite their own references, and it is up to the reader or researcher to judge the validity of those references.

Unlike other encyclopedias, content on the Wikipedia is covered under a Free Documentation License. That is to say, anyone can use the content with few restrictions. It is interesting to note that content from the Wikipedia shows up in published articles all the time. For example, when a news story is written about a person or place unfamiliar to most readers, the writer of the article will often include a sentence or two of explanation, taken verbatim from the Wikipedia.

Some people have described it as adding “reading comprehension” to Internet computers. In other words, the goal is to have the computers be able to comprehend a concept which is not explicit in the text.

For the typical home user, the semantic web would be most evident in search results. For example, suppose you wanted to know what pets Virginia Woolf had. If you do a search for “Virginia Woolf pets”, current search engines will show you webpages about Virginia Woolf that contain the words pet or pets. However, suppose there is a fine webpage which discusses in great detail Virginia Woolf’s relationship with her faithful Irish Setter. If the word pet does not appear on the page, the page does not appear in your search results. However, with a semantic web, the search engine would understand that an Irish Setter is a dog, and that when a dog appears on the page near a proper name, it is likely a pet.

Anther example of a concept that the semantic web would address would be something like color. Consider the question, “What is the main color of the flag of Michigan?” Current search technology will show you pages about colors, about flags, about Michigan, and, hopefully, specifically about the flag of Michigan. However, a semantic web could answer that question directly from a webpage that states, “The flag of Michigan is a crest on a deep blue background”, even though the word color does not appear on the page, because the semantic web would know that blue is a color.

From a more technical standpoint, the semantic web would help make connections between things like stock numbers, product descriptions, and prices. While you can easily understand the relationship on the webpage by looking across a chart, without a semantic web, the computer doesn’t understand the connection.

The implementation of a semantic web is a lofty goal for the future of the Internet.There are many technologies that would have to be standardized and accepted by webpage writers and publishers to make their pages “semantic”.

The issue of net neutrality should not be confused with traffic volume pricing. Paying an ISP or web host for higher bandwidth limits or faster transfer speeds is a normal business practice. No one disputes the concept of paying more for better, faster service.

What net neutrality addresses is the possibility of ISPs looking inside the data packets to see what they are (packet sniffing), and then degrading the service based on what they see (packet shaping).

It would be as if the Post Office could look inside your envelopes and charge more for a Christmas card than it does for a birthday card. Or, using the toll road analogy, suppose two Ford Explorers pulled up to the toll booth. The toll taker would look inside each one, and then charged their toll, or set their speed limit, based on the driver’s appearance.

In practice, the issue of net neutrality usually comes up in the examples mentioned above — multimedia files via BitTorrent and Internet voice calls. ISPs have been accused of slowing down transfer speeds when the data being transferred is one of those two things. There’s no disputing that people who constantly download audio and video files use more than the average amount of bandwidth, but the question is, if they pay for unlimited bandwidth, why should that be a problem?

Another possible point of contention is conflict of interest, for example, with Internet voice calls (Voice over Internet Protocol, abbreviated and pronounced VoIP). Imagine if ISPs had the power to degrade service based on the provider. For example, suppose your ISP was Comcast, but you subscribed to Vonage or Skype VoIP service. Could Comcast degrade your Vonage or Skype service because you didn’t choose Comcast VoIP? Could Verizon degrade your connection to Google because they have a contract with MSN Search?

The issue of net neutrality is far more complicated that what is described here. The important point to know is that net neutrality has nothing to do with the amount of data — it has everything to do with the type of data.

When I moved to Maryland, where horses are part of the local culture, my interest in the Preakness Stakes rose a little bit, too. So over the last thirty years, I, like many other non-horse sports fans, have paid attention to the potential Triple Crown winners, and have been disappointed every time. Just so you know, I have never bet on a horse race, so I have no financial interest in any of this business.

This time was supposed to be different. This time it was supposed to happen. This time there was no reason, other than a flat out injury, that could prevent Big Brown from making history. But it didn’t happen. Instead, I watched the big brown horse fail to make his move on the back stretch and then fade as they turned for home.

The immediate assessment was that there was no injury. The horse didn’t show any signs of breakdown. I turned off the TV. I wasn’t interested in hearing any more details.

I’m just done with the whole thing. I’m done with watching the Kentucky Derby. I’m done with watching the Preakness Stakes. I’m done with watching the Belmont Stakes. I don’t care if a horse wins the Derby and the Preakness. Let me know when someone wins the Triple Crown, because until then, I’m not interested in listening to any more commentary or watching any more races.

Hey, the Phillies are 3 and a half games up in the National League East!

The name cookie comes from earlier computer jargon, and it has no intuitive resemblance to a cookie that you eat. In real life, a web cookie is more like a token or ticket. For instance, when you drop off your suit at the cleaners, they give you a ticket to associate you with your suit, and then you give the ticket back when you pick it up. It doesn’t matter to you how they keep track of your suit, because as long as you have the ticket, you are assured that you will be able to get your suit back.

The same is true of cookies. It doesn’t matter to you, or your browser, what the website is doing behind the scenes, as long as you have the cookie, everything will work as designed. Your browser doesn’t have to remember everything in your shopping cart, and it doesn’t have to remember your color scheme or layout preferences for each website, as long as the cookie can identify you to the web server when you go back.

The length of time that a cookie stays on your computer, or remains active, is part of the data in the cookie itself. Advertising cookies (see below) are typically set for five years, but there is no limit. If the cookie has no expiration date, the browser automatically deletes it when the browser is closed. Cookies that have an expiration date and stay active are called persistent cookies.

Because cookies can be used to track your browsing habits, they do present a certain level of privacy and security risk. However, it’s important to know that cookies are just plain data. They cannot do anything themselves; they cannot start programs or run spyware or install viruses.

Most of the concern arises from the introduction of third-party cookies which are not controlled by the displayed website. For example, you might be looking at a website which has an advertising banner from a different company. This third party can also send a cookie to your browser to identify your computer. Since the advertiser, or the advertising agency, has ads all over the Internet, they can track your web habits on all of the sites they serve. The purpose of these cookies is to create aggregated data for the advertisers, so they can determine things like, people who visited this website also visited that website.

Unlike links, cookies are installed automatically. You don’t have to do anything. In other words, if you see a banner ad on a website, it’s possible that the banner ad already sent a new cookie to your browser or retrieved an old one from your browser. The bad part is that banner ads can be constructed in such a way as to be virtually invisible on the webpage, which means that their sole purpose is to operate cookies. In recent times, it has been demonstrated that it’s possible under certain conditions for one website to hijack another website’s cookies, presenting another security risk.

Cookies serve an important function on legitimate websites and most of the time present no problem. By default, your browser accepts cookies and keeps them until they expire. However, your browser also has tools or options which allow you to adjust the way that your browser handles cookies. If you want, you can have the browser notify you when a cookie is sent, or you can decide to reject all cookies, or delete all cookies manually, or delete all cookies automatically when you close the browser.

Legitimate websites which allow you to set personal preferences often notify you ahead of time that “You must have cookies enabled to use this feature.” And now you know what they mean.

In the US, the two providers are Sirius Satellite Radio and XM Satellite Radio. In order to receive satellite radio, you have to purchase the branded receiver, which can be smaller than an eyeglass case, and you have to pay the setup fees and a monthly subscription. Satellite radio can be set up in your home with connections to your stereo system, or carried in portable devices, but it’s mostly designed for automobiles. The obvious advantage over terrestrial radio is that the satellite signal can blanket a wide land area. With only a few satellites, the service covers most of North America.

Both Sirius and XM have made agreements with some vehicle manufacturers to make their receivers an optional accessory on new purchases. More commonly, you purchase a receiver and install it yourself or have it professionally installed.

Since it is receiving a signal from space, satellite radio requires a different type of antenna. The terminal end of the antenna is a small disc about the size of a Peppermint Pattie®. Like a GPS device, it must be positioned on the outside of the vehicle with a direct line of sight from the satellite to your antenna. In other words, it will not work when the vehicle is under a roof or inside a tunnel or a parking garage. The signal can also be blocked by tall buildings or other obstructions. Be aware that airports and military installations may also block satellite transmissions.

The satellite receiver has no speakers of its own. It has to play through your regular radio speakers in the car. If your car stereo is equipped with an input jack, you can connect the satellite receiver directly and play it as you would a portable music player. Otherwise, you have to use the receiver’s FM signal to play through your stereo.

For most do-it-yourself installations, that means that the satellite receiver becomes its own FM station, and you just set your FM dial to the corresponding frequency. The receiver is powered by a connection with your car’s accessory plug. The disadvantage is that you may experience some interference from actual FM stations, depending on the stations around you. Professional installation offers a cleaner setup with a hard-wired power supply and a hard-wired FM connection.

Both Sirius and XM offer a wide range of programming with over a hundred stations. Each station covers a unique style of music, talk, sports, and entertainment, as well as news, traffic, and weather. For sports fans, it is a choice between Sirius’s NFL coverage and XM’s Major League Baseball coverage. As a subscription service, satellite radio is also open to adult type content, which is clearly identified. Some of the stations are simulcasts of terrestrial radio, so they include the normal commercial breaks, but the music stations are generally commercial-free.

Satellite radio is very appealing to professional drivers, such as truckers on long haul, because the satellite signal remains the same no matter where they go. It is also appealing to anyone who desires commercial-free music or a variety of audio entertainment that is not available on their local radio stations.

In 2007, Sirius and XM announced that they were intending to merge into one service, but such a merger is viewed by some as an anti-competitive monopoly, and as of this writing, no merger seems imminent.

The satellites used for GPS were originally intended for exclusive use by the US Department of Defense, but in 1983, President Reagan declared that the system should be available to the general public. There are currently more than 30 GPS satellites in service, maintained by the US Air Force.

The theory behind GPS is an extension of triangulation, whereby a surveyor can measure distance based on the angle from two different known points. In the case of GPS, its location on earth can be determined by trilateration from three satellites. Today’s more advanced GPS systems use eight or more satellites to improve reliability and accuracy. In order to receive a signal, the receiver, or at least the antenna, must be outside within view of the sky, just like satellite radio.

Obviously, GPS is an important tool for military, scientific, and aviation purposes, but for the consumer, GPS generally takes on one of the following applications:

• Automobile navigation
• Marine navigation
• Wilderness navigation
• Personal navigation

Automobile navigation via GPS is always integrated with a highway mapping program. The GPS receiver may be installed into the dashboard of the vehicle, or it may be a portable device that you can move from one vehicle to another. Some models also include a digital voice feature, so the GPS device can speak to you and give directions in real time. Marine navigation is essentially the same as automobile, when combined with nautical charts.

Stand-alone GPS receivers have become a must-have tool for wilderness travelers, whether they are hikers, hunters, mountain bikers, off-road drivers, white-water rafters, etc. The GPS device can be used to set waypoints and direct the traveler to them. For example, a hunter who plans to wander about an unfamiliar mountain forest can set a waypoint when he leaves his vehicle, and no matter where he roams, he can follow the directions of the GPS back to his vehicle. A hiker can set waypoints along the trail, or wander off the trail, and follow the GPS to backtrack the same path.

Like most other electronic technologies, GPS receivers are getting smaller and lighter. A hand-held GPS receiver is sometimes called a personal navigation device, abbreviated PND. They can also be embedded into other devices, such as cell phones, PDAs, and laptop computers. Any such device that is connected to the Internet or to a cell phone network can have software that enables reverse GPS. In other words, it can send the location information from the receiver to a remote station, so that someone else can track the movements of the PND-carrying person. Reverse GPS is touted as a safety measure for parents and children and as an advanced business practice for employers.

When reviewing or purchasing portable devices, it’s important to differentiate GPS from GPS-like navigation. For instance, cell phones can use triangulation from cell towers to give an approximate location, but they are not nearly as accurate as GPS. Cell phone triangulation is active in most cell phones, which allows emergency services to approximate the origin location of emergency calls.

The accuracy of GPS receivers depends on many natural conditions, but in normal circumstances, consumer devices are usually accurate to within a few feet, which makes them useful for such things as determining distances on a golf course. And because they operate at light speed, GPS can be used to track vehicles in high-speed racing. At the highest level of performance, GPS can be accurate to within a few inches.

There are many different manufacturers of GPS receivers, and the models vary greatly in features and price. Some examples of manufacturers of consumer products are:

• Garmin Ltd
• Magellan Navigation Inc
• Mio Technology
• TomTom International

With audio files, especially music files, the degree of compression is very important to the clarity, richness, and dynamic range of the playback. The compression level of audio files such as MP3 are described in terms of kilobits per second (kbit/s), which is called the bit rate. The higher the bit rate, the lower the amount of compression and the better the quality, but the larger the file size.

Internet music files are often saved and transferred in a 96 kbit/s format, although 128 kbit/s produces a noticeable improvement in the quality of sound, similar to an FM radio broadcast. For orchestral or vocal music, 192 kbit/s is considered to be the minimal acceptable rate. Higher bit rates are generally indistinguishable from a digital CD recording.

With digital video files there are two distinct types of compression. The first type is video which is intended to be played directly over the Internet, in the same way that Internet radio plays audio. This type of video compression runs the full range from high quality video, like the TV shows shown on network websites like ABC.com, down to the highly compressed, low quality video clips like the ones shown on YouTube.

Low quality video is characterized by blurry blocks of color. The compression technique is similar to the one used in JPG photos, but the effect is even more exaggerated in video.

The second type of digital video is intended to be equivalent to, or better than, regular television programming. The idea with this type of video is to encode the files to a smaller size using compression algorithms, then allow the player in your home to de-compress or decode the file to its original quality. Digital cable and satellite TV are examples. It’s important to know that all high-definition TV is digital, but not all digital TV is high-def.

A more recent development in digital television is having movies and shows which you purchase and download over your broadband connection to play on your TV. Television which comes to you over the Internet is called Internet protocol television, abbreviated IPTV. Once again, to save on bandwidth, IPTV may be compressed.

Early file compression techniques were aimed at text files. It is relatively easy to reduce the size of text files with some simple rules and codes for common repetitions. For example, you could remove the space after every comma and period, remove the u after each q, change all th’s to *, etc. With a few such rules, text files can be compressed to a fraction of their original size. Of course, to get the original file back, you have to know what the compression rules were.

Compression today is much more important in digital media files. Most people are familiar with the JPG (usually pronounced jay-peg) photo format. JPG is a compression system that is based on human perception. For example, a raw digital photo of the sky may contain thousands of shades of blue, which is more than the human eye can distinguish. So JPG compression smooths out the blues to just a few distinct shades, which reduces the amount of data necessary to display the photo.

The difference between photo compression and text compression is that some of the original data is actually lost. You can’t get back the thousands of shades of blue once the photo is compressed. This type of compression is called lossy compression, because there is loss of some of the information in the process. In lossless compression, all of the original data is preserved. Most graphics programs allow you to set the level of lossy compression, as a percentile, when saving or converting JPG files. The level of compression will determine how sharp or fuzzy the final photo will be.

Read more about Audio and Video Compression.

While megapixels and photo dimensions are not the exact same thing, it’s reasonable to think of them relative to each other: the more megapixels a camera has, the larger the dimensions and the higher the quality of the photo it produces. There are other differences among cameras, notably the quality of the lens and the size of the photo sensors, which impact the overall quality of the original photo. In the case of a compact point-and-shoot camera, there doesn’t seem to be much advantage to having more than 8 megapixels for producing photos to be displayed on a computer or printed in a reasonable size.

A pixel is a picture element, the smallest dot of color that makes up the digital photo. The more pixels that a photo contains increases the detail that the photo can hold.

It is a common misconception propagated in movies and television that you can “blow up” a digital photo and get more detail. But if the pixels weren’t there in the first place, creating more pixels won’t create more detail. In other words, if a person’s face is recorded on a digital photo as 4 tiny blocks of color, if you blow it up, it just becomes 4 bigger blocks of color.

Resolution is the general term used to describe the amount of detail that a photo contains. It is often used interchangeably with the pixel dimension size, but the comparison is only useful when the image is the original file from the photo sensors, and not simply re-sized to larger dimensions. In other words, an original photo taken with a digital camera that produces a 2048 x 1536 pixel image is a higher resolution than a photo taken with a cell phone at 640 x 480 which has been resized to 2048 x 1536.

Resolution is sometimes expressed in dots per inch (dpi), which refers to the number of pixels that are displayed on a monitor or printed on paper. However, changing the dpi has no effect on the actual detail contained in the photo; it merely changes the amount of detail which is displayed or printed.

Digital photo compression and digital photo size are two different concepts. Two photos can be the same size but have different levels of compression. The result would be a lower quality photo of the same pixel dimensions, but the file size (in bytes) would be smaller. This type of compression is commonly used for website construction, where the quality of the photo is not crucial.

Here are two versions of the exact same photograph of Hoover Dam, resized from an original 2160 x 1440 digital photograph to a small 375 x 250 web image. The top photo was simply resized without any further compression. The file size is 100,226 bytes.

The lower photo was compressed to a file size of merely 13,832 bytes — less than 15% of the size of its counterpart!

For the purpose of a small web photo, the advantages of compression for lower bandwidth and faster page loading are self-evident. But it’s important to remember that compression of this type is not reversible from the finished photo. The compressed file is fine for viewing on this webpage, but it is unsuitable for printing or for any other type of manipulation.

Read an introduction to Data Compression.