Via Google blog
Today, we’re announcing the completion of a new web indexing system called Caffeine. Caffeine provides 50 percent fresher results for web searches than our last index, and it’s the largest collection of web content we’ve offered. Whether it’s a news story, a blog or a forum post, you can now find links to relevant content much sooner after it is published than was possible ever before.
Some background for those of you who don’t build search engines for a living like us: when you search Google, you’re not searching the live web. Instead you’re searching Google’s index of the web which, like the list in the back of a book, helps you pinpoint exactly the information you need. (Here’s a good explanation of how it all works.)
So why did we build a new search indexing system? Content on the web is blossoming. It’s growing not just in size and numbers but with the advent of video, images, news and real-time updates, the average webpage is richer and more complex. In addition, people’s expectations for search are higher than they used to be. Searchers want to find the latest relevant content and publishers expect to be found the instant they publish.