Indexing in PostgreSQL is a feature that improves query performance by allowing faster data retrieval.Pros of indexing include faster query performance, optimized sorting and filtering, and enhanced performance for unique constraints.Cons of indexing include slower insert, update, and delete operations, increased storage requirements, and overhead in index maintenance.Different index types in PostgreSQL include B-Tree, Hash, GIN, GiST, BRIN, and SP-GiST, each with its own use cases.