Google has from May 2010 onwards come up with major changes. First being the May Day update they call it that because it took place between 28th of April to 3rd of May. The second change is the formal announcement of Google Caffeine going live from all Google data centres on 8th of June at the Search Marketing Expo – Seattle.
The May Day update is an algorithmic change which has been intentionally made to improve the quality of long tail keywords search results. On the other hand Google caffeine is a new web indexing system.
According to Google they came up with this new indexing system to keep up with the evolution of the web and to meet rising user expectations. Google further has mentioned on its blog that 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.
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.
The main objective of Google Caffeine is to index the web faster to offer more fresh content and results to the users. Hence, speed and fresh content is the future of the web.
View the following video to listen to what Matt Cutts has to say about the evolution of the the Google indexing architecture from 2001 onwards and Google Dance ( the term Google Dance I am sure must be familiar to all the SEOs who are optimizing sites since 2002) .