Stoicism is a very old philosophy, created in the time of the ancient Greeks (around 300 BC). But it became very popular in the Roman empire in all levels of society, from slaves to emperors. Some of the most famous Stoics are Cato, Seneca and Marcus Aurelius.
The basic idea
The basic idea of Stoicism is that you take the obstacles in your life and turn them into your advantage and the notion that you should control the things that you can control and accept the things that are outside of your control. This is similar to the concept of the circle of influence and the circle of concern, mentioned in 7 Habits of Highly Effective People.
It all boils down to being in control of things instead of letting things control you.