A commonly-requested feature in search applications is autocomplete or search suggestions. The basic idea is to give users instant feedback as they’re typing. Implementations of this feature can vary — sometimes the suggestions are based on popular queries (e.g., Google’s Autocomplete), other times they may be previews of results (e.g., Google Instant). The suggestions may be relatively simple, or they can be extremely complex, taking into account things like the user’s search history, generally popular queries, top results, trending topics, spelling mistakes, etc. Building the latter can consume the resources of a company the size of Google, but it’s relatively easy to add simple results-based autocomplete to an existing elasticsearch search application.