OpenAI Gym has modeled a number of classic control theory problems as RL environments, including the inverted pendulum problem we already worked with in CartPole.
We'll go through some of the more popular environments in the next section. Keep in mind that Gym environments have a shared interface that lets you write generalized algorithms that can potentially be used to solve more than one environment.
You can also create your own environments and upload them to Gym if you carry out the full installation. Instructions are available in the Gym documentation.