Link: Welcome to Steam
Seeing this for the first time, I can definitely say that now both Mac and PC users can rely on this site to get their favourite games on their laptops or PCs without the inconvenience of using the CD/DVD which in my honest opinion is slowly becoming obsolete making way for the higher storage Blu-Ray Discs.
A question to the readers : When was the last time you used a CD/DVD to play a game?