The speaker, Jacques, begins "All the world's a stage" by asserting that life is like a stage on which "men and women merely" play roles. They play different parts throughout their lives, as the speaker is now. In the bulk of this monologue, the speaker spends time going through the seven ages of man.
One starts in infancy, moves through childhood, and into the best part of their life when they're a lover, soldier, and judge. Later, they lose control of their senses and eventually can't take care of themselves.