Caffeine is Google’s new indexing system which is said to provide 50% fresher results for web searches than the previous iteration of their indexing system. According to Google, their previous indexing system comprised of different levels, some refreshed at faster rate than others and to refresh a layer they had to analyze the whole web creating a delay between brewing the page and serving it hot .But, Caffeine on the other hand analyzes the web in small portions and update the search index continuously and globally.

This is what Google has to say about caffeine
Caffeine lets us index web pages on an enormous scale. In fact, every second Caffeine processes hundreds of thousands of pages in parallel. If this were a pile of paper it would grow three miles taller every second. Caffeine takes up nearly 100 million gigabytes of storage in one database and adds new information at a rate of hundreds of thousands of gigabytes per day. You would need 625,000 of the largest iPods to store that much information; if these were stacked end-to-end they would go for more than 40 miles.
Original Post on Google’s Blog
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