How are stage directions used in a drama, and why are they used?

in a simple form

Stage directions are instructions provided in a play script to guide actors on how to move and speak on stage. They are used to help actors understand the physical actions, expressions, and movements required for a scene. Stage directions also help set the tone, mood, and atmosphere of the play, providing important context for the actors and directors. They are essential for bringing the script to life and ensuring that the playwright's vision is realized on stage.