Most drainage calls we get start the same way: a corner of the yard that stays wet for days, a patio that holds a puddle, or water sitting against the slab after every storm. The fix depends on where the water comes from and where it can go, and it's rarely a one-size answer.
A French drain is a gravel-filled trench with a perforated pipe that collects water moving through the soil and carries it downhill to an outlet. It's the right tool for soggy ground, seepage along a fence line, or water pushing against a retaining wall. It does not work well for surface water that arrives fast in a downpour.
Catch basins and channel drains handle that surface water. A basin at the low point of a patio or lawn, or a channel drain along the edge of a slab, captures runoff and sends it through solid pipe to daylight or a pop-up emitter at the curb. Downspouts should be tied into the same system rather than dumping next to the foundation.
Many yards need both: a channel drain at the patio edge, a French drain along the wet side of the lot, and everything sloped to a single outlet. Before anyone digs, walk the yard during or right after a rain and note where water enters, where it sits, and where the ground is lowest. That ten minutes tells you more than any brochure.