# Why are Invariants so special?

1. ### NoodleDurh

19
I only ask, because I noticed that the Euler Characteristic is an invariant and pops up in differential geometry as the G-B theorem. so could some one explain why they are special.

2. ### HallsofIvy

40,667
Staff Emeritus
"Invariants" don't change! That makes them much easier to work with than things that are changing.