DSL (Digital Subscriber Line) has become pretty standard in most homes and places of business in recent years since the explosion of the internet. DSL, sometimes referred to as XDSL, is a general term for a family of technology. Within the DSL family, there are several different kinds of DSL, each with its own unique features and benefits.

Like the original dial-up connections, DSL uses your phone line to connect. The difference is the speed- DSL is much faster than its predecessor. The typical download speed for consumer DSL ranges anywhere from 256 to 24,000 kbits/s. Speeds vary depending on many factors such as the DSL technology used, line conditions and the level of service the customer has paid for.

DSL is popular among consumers because of its low cost and its ability to use pre-existing phone lines without interruption of service or without having to install any expensive hardware. DSL works with your existing phone lines by using a high frequency, while the telephone line uses a low frequency. In this way both services are able to run on the same line simultaneously.

ADSL

ADSL (Asymmetric DSL) is the most popular consumer DSL. ADSL gets its name from the fact that its upload and download speeds are asymmetrical. That is to say that download speeds are generally much faster than upload speeds. It's not random that it's like this. Most consumers prefer to have faster download speeds because they tend to download much more than they upload. It makes sense for telcos to meet consumer demand by providing faster download speeds and dedicating more bandwidth to downloading than to uploading since most users don't upload nearly as much as they download.

SDSL

SDSL (Symmetric DSL) is different from ADSL because instead of having different upload and download speeds, both speeds are the same- they are symmetric. It's used mostly for small to medium sized-businesses, typically who host their own servers on-site. SDSL allows users to upload more information while still maintaining its speed. Because of the extra upload speeds, SDSL is more expensive than ADSL, making it impractical for the average consumer. On the other hand, businesses that need to upload lots of information will benefit from the faster speeds and the extra cost will be worth it.

VDSL or VHDSL

VDSL (Very High Bitrate DSL) is the highest speed DSL available on the market today. It works by using a single flat untwisted or twisted pair of copper wires. Because the speeds are so fast, VDSL is capable of supporting HDTV, VOIP and regular internet access over the same connection. The new generations of VDSL are so fast they're able to support over 100 Mbits/s of both downloading and uploading. Because of its versatility telcos are able to offer bundled packages which include all the above services plus video-on-demand. Unfortunately, the cost of VDSL is currently too high for it to be practical for most people. However, in the future as prices drop, VDSL will be a viable option for most people.