Bandwidth is the fulcrum on which Net surfing hinges. High bandwidth lets you cruise the Net with ease and speed. Low bandwidth, well, let's just say it makes Web surfing like walking five miles to school, uphill, both ways, through the snow.

The easiest way to explain bandwidth is to use a "pipe" metaphor: The bigger your pipe, the more stuff you can put through it. On the Internet, the "stuff" is the bits of data that make up Web pages and your "pipe" is the connection you have with the Net; this can include the particular phone line and modem you have.

Transmission speeds are measured in units called bits per second, or bps. A bit is the smallest amount of information a computer can understand.

Today the most common modem speeds are 28.8 Kbps and 56 Kbps (that's kilobits - or thousands of bits - per second), but modems are always improving. Since 56 is obviously faster, and therefore better, than 28, watch for those 56 Kbps to become a de facto standard soon. ISDN (integrated services digital network) connections, which can transmit data up to 128 Kbps are not supported by every Internet service provider, and there are several competing technologies still vying to become the standard.

Another up-and-coming technology is the cable modem. These modems can transmit data at up to 10 Mbps (megabits per second) and are probably the fastest connection you can get in your home now. Cable modems use the same wires as your cable TV, but are offered only in a few neighborhoods. ADSL (asymmetric digital subscriber line) is another fast new technology, but it's very expensive. ADSL splits your phone line into three different channels: one for voice, one for uploading data, and another for downloading data. ADSL has very fast download speeds (up to 9 Mbps), but the upload speed is not nearly as fast, maxing out at about 640 Kbps.

There are some things to take into consideration when you're thinking about bandwidth. Just because you're surfing at work on a T1 line doesn't mean that pages will always load whiz-bang fast. Web pages can only be served as fast as the server (the computer they're stored on) can deliver them. So if a Web page is on a server that has an ISDN connection to the Internet, then you'll only get it at a maximum rate of around 128 Kbps. Another thing is that, just like the Bay Bridge, the Internet gets clogged during rush hour. If a lot of people are surfing a site at one time, the speed at which the pages can be served will be slow.