Smart full-text search
A good quality of results is reached if the documents are properly indexed depending on the application. Stems can be taken into consideration or even synonyms can be used. Leaving out so-called stop words such as "the" can also improve the quality of results.
Auto-complete and auto-suggest
Auto-suggest offers users of a search box relevant suggestions already while entering the search item. Just a few letters lead the user to the search item. A term is easily completed and afterwards searched for by clicking on the term or a selection.
Faceting (also called after-search navigation or category navigation) is a helpful tool to users for refining search results primarily in e-commerce systems. The display of possible hits in the next filtering step simplifies the navigation.
An often used function is the search for a specific word, word combination or complete sentences. These often have to be highlighted to display sources more clearly and to facilitate the search process for the user primarily in extensive texts.
Smart searches provide easy similarity searches. If there are no or only a few search results for the desired search item, this search item is analyzed and matching alternatives expand the search result. A fuzzy search is also possible to find similar items.
A geo-search, also called spatial search, rounds out smart searching. For example, a good proximity search yields the search results in reference to the given location. Further options involve the search within defined areas that are geometrically described.