This document provides an overview of search functionality in Drupal 8. It discusses that Drupal 7 had two main search solutions that could not be combined, while Drupal 8 search aims to integrate these solutions and provide a common, flexible search system out of the box. It describes the basic architecture including servers, indexes, backends, trackers, datasources, and processors. It also outlines changes for Drupal 8 like supporting multiple entity types in one index and multilingual/multisite search.