what is Motion compensation.how does it help, can anyone one explain in detail

[avengerevenge]

hello everyone,

can anyone tell me what is motion compensation.
i know how to use avisynth(not perfectly), how does it help
in encoding videos, first of all how what does it do,
i dont know the concept,
i know tools like MVtools are used for doing that,
i tried to read the official scite of MVtools,
but understood nothing because its very deep
i am confused, can anyone guide me through this,
just explain me how it helps in encoding.

i am in intermediate stage(not a newbie nor expert or professional)

i would really be thank full to you.