The term "time series" is popular (again) in database circles. What is it and what's the point? Clearly, a traditional relational database like PostgreSQL can deal with time and with series. So why is time series a special use case? In this presentation, I want to look beyond the marketing a bit and analyze what the true technical characteristics of a time series database are and what use cases drive it. Then we can analyze how PostgreSQL handles these requirements, which workarounds are handy, and where improvements would be necessary. In PGCon tradition, this presentation is both guidance for users and a call to action for developers.