GOG Galaxy is the official client for GOG (formerly Good Old Games) with which you can download and play all the games you've purchased on this service. You can obviously buy other games, too. The main function of GOG Galaxy is making life easier for its users. Thus, like Steam, it lets you receive automatic updates for all your installed games. This didn't used to be necessary, but it's very useful now especially for more modern releases like The Witcher 3. From GOG Galaxy, you can visit GOG.com forums and chat directly with friends who use the client. Moreover, within the folder for each game in your library, you can check out and download extra content: manuals, maps, illustrations, soundtracks, and so on. GOG Galaxy is a super interesting client for GOG games especially because, unlike Steam or Origin, you DON'T have to use it in order to play. You can use GOG Galaxy if you want, but can opt not to if you don't have an Internet connection or simply don't fancy opening it.
