If you have been developing Lightning Components for a while it is probable that you have come up against the feared Locker Service. If you are aware of Summer 18 Locker Service changes, you will know that, luckily, Locker Service restrictions have been relaxed. However, there are still some libraries that are considered unsafe and that cannot run within this context. For those cases, lightning:container comes to the rescue!
So, what’s the frightening Lightning Locker Service? It is a combination of security features that have been implemented for you in order your Lightning Components are secure, and other components don’t break yours! So, no frightening at all, right?