big o - Complexity. Why dont constants matter?

Question

Can someone please explain to me in a simple way why constants don't matter when it comes to big O notation? Why does the complexity stay the same when you add a constant. This is not a homework question I just want to understand this better. Let me get this straight big O is for seeing the behavior of a function as it approaches infinity right?

I got it. Thanks so much everyone.

Answer 1

It does not matter for complexity theory, which is interested only in how the function scales as the input size grows.

A constant does not affect how the function behaves as input sizes grow towards infinity at all.

However, if you are interested in actually running a certain piece of code, you may very well be interested in a large constant overhead and how the function performs for smaller input sizes.

Difference between complexity theory and practice.