Is a process that occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and gradually moves away from the ridge.

I don't know if you are supposed to explain or name it, but I'll just do both.

Well, the process is called sea-floor spreading. It makes new crust at mid-ocean ridges, and the older crust, when it gets away from the ridge, gets recycled from a deep-ocean trench (Or subduction zone, I can't remember). That is why the Earth don't get bigger