Indexes are one of the core features of all the database management systems (DBMS). Indexes have a very long history in PostgreSQL, which has quite a rich set of index features. PostgreSQL has B-Tree, Hash,  GIN, GIST, and BRIN indexes. And because the development around indexes is still going on, PostgreSQL 13 provides some enhancements. [&]

https://www.percona.com/blog/2020/09/10/index-improvements-in-postgresql-13/