How do pools work (from a plumbing perspective)?

How do pools work? I’m trying to understand the feasibility of adding a pool to my yard, and want to understand the plumbing and engineering requirements.

The plumbing of a pool is to serve a couple purposes. It transports the water to the filter and/or heater and back into the pool, and it discharges water from the pool. The plumbing is usually pretty basic and consists of PVC piping in most cases.