Google Instant Search allows searchers to see content as they type their query into the search engine box, revealing results before they finish typing based on it’s ability to predict the search query.
The promise of Google Instant Search was to deliver better search results in a shorter time frame saving users an extra 2-5 seconds per search.
The predictions feature guides the searcher by showing the top prediction in grey text so searches can stop typing and see results appear instantly as they type. It is facilitated by Google’s autocomplete algorithm which predicts searches in real time, offering searches that might be similar to the one the user is typing. It is based on other users’ search activities and if you have google web history enabled and are signed into your google account, it may show some predicted queries drawing on historical searches.
If the user upon seeing the search results decides they want to adapt their search they can re-frame their search and the results will only render new results without displaying results already served.
Google instant was predicted to change search behaviour. You could expect search volume queries to change given that the first keyword will influence subsequent words, affecting businesses with longer tail search terms.
A report released on the impact of search behaviour one month after Google Instant was released shows that Google instant hasn’t had a major impact on search behaviour. A discussion of the study and Google Instant by webmasters from an SEO/SEM perspective appears here at webmaster world.