The Internet and the Web started as communications media through which users could request data. But it didn't take long for some enterprising souls to see the value in "pushing" data to users based on predefined preferences. In the push model, users don't hunt their way through what the Web has to offer. Instead, they simply enter a variety of interests and needs into a server-side database. Then the server collects all the information it feels is relevant and pushes the data to the user's desktop via client software, which is sometimes a standard browser but is often a proprietary interface like PointCast or the Yahoo News Ticker.
See also: Active Channels