Google Suggest is one of the main features of Google search. It was introduced in 2007 and quickly became a core part of Google search. Basically, every time a new search is performed on Google, many things are going behind the scenes.
The sophisticated Google algorithm attempts to suggest search queries that best match the entered term. Suggested keywords appear under the search box. Generally, you will see 3 - 5 suggestions, sometimes however 10 suggestions are displayed.
A user that is performing the search can click on any keyword from the Google autofill list and immediately see the search results page. This experience is both fast and convenient.
Note: The Google autocomplete function was previously known as Google Suggest.