HTTP, Hypertext Transfer Protocol
http is based on request-response model. If you don't send requests, there will be no responses from any servers at all.
Limitations
If you have a lot of blogs and news groups to read frequently, the request-response behaviors will cost you time to examine each content source respectively. Unfortunately, you may check into websites that have no updates since you checked in last time.
RSS 2.0
RSS 2.0 is a syndication standard using XML. With RSS 2.0, you can subscribe to the source feeds in RSS 2.0 format. Many RSS 2.0 readers can keep an unread list for you, so that you always see the latest updates from the information sources you subscribe to.
Further Reading
pp. 183-185 of Textbook.
