Grow hair on the chin and nowhere else and you have the classic goatee. It survived every beard trend of the last fifty years because it solves a real problem: it adds visual length and structure to the lower face without asking for full-beard growth or full-beard patience. It also works with patchy cheeks, since the cheeks stay shaved anyway. The line between a goatee and a circle beard is the moustache: add one and connect it, and you have left goatee territory.
Who does it suit?
Strongest on round and heart faces, where the chin needs definition. On an already long face it stretches the proportions further, so oblong faces should look at fuller cheek coverage instead.
How to maintain it
Shave cheeks and neck every two or three days, and keep the chin outline crisp with a trimmer. Length is taste, but the edges are the style.