pgbench is a simple benchmarking tool for testing the performance of PostgreSQL databases. It simulates multiple clients connecting to the database and executing transactions, allowing users to measure how well the database handles concurrent workloads. The tool comes with built-in scripts for common transaction types, but users can also create custom scripts to suit their specific needs. By providing detailed statistics on transaction rates and response times, pgbench helps database administrators identify performance bottlenecks and optimize their systems effectively.