Google Reader is an RSS feed reader. What is RSS? According to the definitive source of everything (Wikipedia):
RSS (originally RDF Site Summary, often dubbed Really Simple Syndication) is a family of web feed formats used to publish frequently updated works—such as blog entries, news headlines, audio, and video—in a standardized format.
Here's a screenshot of part of my Google Reader list:
Use Folders! - You can organize your RSS feed subscriptions in folders to make it easier to keep up with dozens of different sources