Elasticsearch is software that helps to quickly search through many and various types of data and perform analyses on them. Elasticsearch searches through your website data, but also through files such as PDFs. And the software does that very cleverly. As a developer, you can set up Elasticsearch to deal with uncertain data. This ensures that website visitors still get relevant search results if they misspell a search term. What's more, Elasticsearch is - as the name suggests - an elastic system. In other words: scalable.