PlayStation Communities is an official app from Sony thanks to which you can take a look at all your PlayStation 4 communities, look for new communities for games that interest you, and of course join them easily.
From the main tab in PlayStation Communities you can manage your communities – the ones you belong to. You can view the posts, notices, and news for those communities and, if you want, leave them.
The second tab in PlayStation Communities, Discover, gives you the option to look over the different PS4 communities divided up by games. You can also see which communities your friends are in or which ones are trending.
PlayStation Communities is a very useful app for managing your PS4 communities, thanks to which you can discover new ones to be part of.