TLDR Web Dev · MISCELLANEOUS

UNDERSTANDING THE BM25 FULL TEXT SEARCH ALGORITHM

emschwartz.me14 min read

Summary from the TLDR Web Dev newsletter

The BM25 algorithm is a full-text search algorithm widely used in systems like Lucene/Elasticsearch and SQLite. This post goes over the algorithm's mathematical components - inverse document frequency (IDF), term frequency, and document length normalization - showing how they contribute to a relevance score.