What is an analyzer in Elasticsearch?

An analyzer is a pipeline applied to text fields during indexing and search that transforms raw text into tokens stored in the inverted index. An analyzer consists of three components: a character filter (optional, pre-processes the raw text, e.g., stripping HTML), a tokenizer (splits text into tokens, e.g., the standard tokenizer splits on whitespace and punctuation), and one or more token filters (transform tokens, e.g., lowercase filter, stop word removal, stemming). The default standard analyzer tokenizes on whitespace/punctuation and lowercases. Choosing the right analyzer is critical for search quality.