If you've never heard of a french drain, don't worry. It's not a drain central to France, nor is it some weird food dish. It's a very significant drain that goes by a few different names (i.e., trench drain, filter drain, weeping tile, rock drain, etc.). It's a trench filled with rocks or gravel that redirects surface water and groundwater away from where it shouldn't be through a perforated pipe system.
The primary purpose of the french drain is to make sure that any groundwater or surface water doesn't come into contact with the foundation of a building, thus weakening it. The act as sort of a retention pond but there is no open, standing water. They remove a lot of unwanted moisture from the soil and can also distribute water like in a septic drain field. They're installed with a slight slant that keeps the water from ever getting to where you don't want it to be.
The lifeline of a french drain is quite a few years. They do tend to become clogged though, and debris from nearby trees or shrubbery can add to this issue. It's a great idea to practice lawn maintenance and make sure that type of thing doesn't happen too often. The cost for installation of a french drain is between $750-$1250, that's generally a 30'-50' long drain pipe that's being put in the ground.
If you're not sure if you need a french drain, consider the following:
Do you have a lot of standing water after it rains? Is your lawn always feeling soggy or your driveway still wet? Is your home partial to flooding? If you answer yes to any of these, then a french drain might be the answer to your problem!