Google Instant - Search as you type

Google started rolling new search feature called Google Instant. Google Instant is search-as-you-type. It’s a simple and straightforward idea—people can get results as they type their queries.The most obvious change is that you get to the right content much faster than before because you don’t have to finish typing your full search term, or even press “search.” Another shift is that seeing results as you type helps you formulate a better search term by providing instant feedback. You can now adapt your search on the fly until the results match exactly what you want.

According to google Google Instant can save 2-5
 seconds per search and before Google Instant, the typical searcher took more than 9 seconds to enter a search term, and they had also seen many examples of searches that took 30-90 seconds to type.
Google Instant feature can be turned on or off by changing the options in the google search preference.

Google Instant at present is rolled-out to users on Google domains in the US, UK, France, Germany, Italy, Spain and Russia who use the following browsers: Chrome v5/6, Firefox v3, Safari v5 for Mac and Internet Explorer v8. Users on domains other than Google.com can only access Google Instant if they are signed in to a Google Account.

Benefits

Faster Searches: By predicting your search and showing results before you finish typing, Google Instant can save 2-5 seconds per search.
Smarter Predictions: Even when you don’t know exactly what you’re looking for, predictions help guide your search. The top prediction is shown in grey text directly in the search box, so you can stop typing as soon as you see what you need.
Instant Results: Start typing and results appear right before your eyes. Until now, you had to type a full search term, hit return, and hope for the right results. Now results appear instantly as you type, helping you see where you’re headed, every step of the way.