From the definition of Big O, it states that there should be a function $g(x)$ such that it is always greater than or equal to $f(x)$. Or $f(x) \le cg(n)$ for all values of $n > n_0$. What I'm not able to understand is what is its importance in Big oh notation. Every question explains what is big-Oh and what how it uses useful. But I'm not able to understand what is $c$ actually in big-oh. There might be answer which I'm not able to get it due to its technical jargon.
Can someone explain me this in simple terms?