Keyword search

Keyword search is a retrieval method that matches specific user-input terms against an index to return relevant documents.

Keyword search remains the bedrock of information retrieval by mapping user queries directly to indexed tokens. It relies on algorithms like BM25 and TF-IDF (Term Frequency-Inverse Document Frequency) to score relevance based on how often a term appears in a document relative to the entire corpus. While modern systems often layer semantic or vector-based logic on top, the core utility of keyword search lies in its precision for exact matches (names, error codes, or specific part numbers). By utilizing inverted indices, platforms like Elasticsearch and Solr can scan millions of records in milliseconds, providing a high-speed, predictable baseline for any discovery architecture.

https://www.elastic.co/guide/en/elasticsearch/reference/current/full-text-queries.html