How to make a description of the functions inside the unit itself?

Question

C++ / C#

I remember when I set one of the assets, about a year ago, there, next to each variable and button in the script, a window popped up on hover explaining what this button or variable does.

Here's an example I threw in, somehow it was, only the window itself was yellowish, all I remember, excuse me.

Answer 1

[Tooltip("blabla")]
public int npumep;