[Flexibility Friday] Biggest "bang for your buck" exercises and stretches

Welcome to Flexibility Friday. The point of this thread is to discuss flexibility - techniques, tools, struggles, and hardships.

This week's topic is slightly different than the last few weeks. Today we will discuss the most beneficial exercises and stretches that you can do. These are things that you feel that everyone should be doing for their general flexibility and mobility. A "potluck", if you will.

(This is, of course, open to all questions regarding flexibility. Feel free to ask)