Locking is critical for providing high concurrency for any database --- you can't fully utilize your hardware if locking is throttling its use. This talk explores all aspects of locking in Postgres by showing queries and their locks; covered lock types include row, table, shared, exclusive, and advisory lock types. The high concurrency provided by Multiversion Concurrency Control (MVCC) is also covered. The talk will include analysis of locking on a running system.