How do I measure my room in M2?

Hello there, I'm curious about how one would go about measuring the square meterage of a room. I've heard that it's an important factor to consider when it comes to things like real estate and interior design, but I'm not quite sure how to do it accurately. Could you please explain the process to me in simple terms? I'd appreciate any tips or tricks you might have for ensuring that my measurements are as precise as possible. Thank you in advance for your help!