Match moving (also known as camera tracking) is a technique used in visual effects and post-production to integrate CGI or 3D elements into live-action footage so they appear to be part of the same scene. It works by analyzing the motion of the camera in a shot and recreating that motion in 3D space.
You shoot a video of your friend walking with your phone, and the camera is moving too. Now you want to add a flying robot or text that stays in place on the wall. Match moving helps the computer understand how the camera moved, so your animation moves with it and looks real.