Ko Samui is a heavily visited island in Southern Thailand. It is quite busy nowdays, even in the off-season. It wasn't always that way - before Bangkok Air built an airport on the island, it was quite a journey to get there.
The airport is owned by Bangkok Air, and for someone new to Thailand this must seem pretty cool. The airport has gotten pretty bust, and there are plans to expand it, or even build a second airport on the isalnd.