The clique thing was a big deal in high school. You might be surprised to know that in many workplaces, cliques live on.
On one hand it’s natural for employees to build relationships. The question you should be thinking about is how cliques affect the workplace.
If you need some hints about potential problems, here are two. Those in a group might suffer from group think. Those outside might do some bad stuff as a result of feeling scorned and rejected. This article helped me think about some of those consequences.