Compression programs are used to make files smaller so they take up less space, which is extremely important when transferring files over the internet.
WinZip is the most commonly used program for compressing. However, it is shareware.
WinRar usually compresses files better than Zip compression. However the format is relatively new, and therefore less used.
FACT: It takes about half a second for a server to respond to a request sent via the internet. TIP: If your page has 10 very small images - each with a size of 100 bytes - it will take longer to load than had it been a continuous stream of 1000 bytes.