Search engine indexing collects, parses, and stores data to facilitate fast and accurate searching. Index design incorporates interdisciplinary concepts from linguistics, cognitive psychology, mathematics, informatics, physics, and computer science. Popular search engines focus on the full-text indexing of online, natural language documents. Media types such as video and audio and graphics are also searchable.
The purpose of storing an index is to optimize speed and performance in finding relevant documents for a search query. Without an index, the search engine would scan every document in the corpus, which would require considerable time and computing power.