# Elasticseach: Default Similairty Algorithm and BM25 giving same results **URL:** \ **Category:** Elasticsearch\ **Created:** [October 15, 2018, 10:31am UTC](https://discuss.elastic.co/t/elasticseach-default-similairty-algorithm-and-bm25-giving-same-results/152470 "2018-10-15T10:31:16Z")\ **Posts on this page:** 1\ **Showing post:** 11
**Author:** ![abdon](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/abdon/32/9195_2.png) [@abdon](https://discuss.elastic.co/u/abdon)\ **Post date:** [October 17, 2018, 6:29am UTC](https://discuss.elastic.co/t/elasticseach-default-similairty-algorithm-and-bm25-giving-same-results/152470/11 "2018-10-17T06:29:14Z")
I would say that generally BM25 is great for longer fields. It is really designed for that full-text search use case. If you want to learn more about BM25, we have a great 3-part blog series on our website: > **[Practical BM25 - Part 1: How Shards Affect Relevance Scoring in Elasticsearch](https://www.elastic.co/blog/practical-bm25-part-1-how-shards-affect-relevance-scoring-in-elasticsearch)** > > Similarity ranking (relevancy) in Elasticsearch relates directly to the amount of shards in your index. Learn more about how shards and relevancy are related, as well what you should consider when tuning search results. > **[Practical BM25 - Part 2: The BM25 Algorithm and its Variables](https://www.elastic.co/blog/practical-bm25-part-2-the-bm25-algorithm-and-its-variables)** > > BM25 is the default similarity ranking (relevancy) algorithm in Elasticsearch. Learn more about how it works by digging into the equation and exploring the concepts behind its variables. > **[Practical BM25 - Part 3: Considerations for Picking b and k1 in Elasticsearch](https://www.elastic.co/blog/practical-bm25-part-3-considerations-for-picking-b-and-k1-in-elasticsearch)** > > Learn about best practices and other considerations before modifying the b and k1 values of the BM25 similarity ranking (relevancy) algorithm used by Elasticsearch. --- _[View the full topic](https://discuss.elastic.co/t/elasticseach-default-similairty-algorithm-and-bm25-giving-same-results/152470)._