In this talk, Jimmy Angelacos discusses some common mistakes and misconceptions that people make when using Postgres as a database. He starts by highlighting some bad SQL practices, such as using the "not in" operator incorrectly and not properly using the "between" operator. He then discusses improper usage of certain data types, such as using naive timestamps instead of timestamp TZ, and using the "money" data type instead of numeric for financial calculations. Jimmy also explains why certain features, like table inheritance and rules, should be avoided in favor of more modern alternatives. He then touches on performance issues, such as using too many database connections and turning off auto vacuum. Finally, he emphasizes the importance of proper security practices, such as avoiding the use of "trust" for TCP/IP connections. Overall, the talk aims to educate developers and administrators on how to avoid common pitfalls when working with Postgres.