One of the most effective features of a search user interface is automatic/instant-search or completion of query input in a search input box. It is typically displayed as a drop-down menu that appears automatically after typing. There are several ways this can work:
Instant-search: Here, the menu is populated with search results. Each row is a document, just like the regular search results are, and as such, choosing one takes the user directly to the information instead of a search results page. At your discretion, you might opt to consider the last word partially typed. Examples of this are the URL bar in web browsers and various person search services. This is particularly effective for quick lookup scenarios against identifying information such as a name/title/identifier. It's less effective for broader searches. It's commonly implemented either with edge n-grams or with the Suggester component.
Query log completion: If your application has sufficient query volume...