An absolute minimum is a point on a curve or surface where the value of the function is less than all other points. In other words, it is the lowest point on the entire curve or surface.
This can be described formally by saying there exists an absolute maximum of the function
If a function is continuous over a closed interval, then there exists an absolute minimum within that interval. To find the absolute minimum check all the critical point within the interval and both the endpoints of the interval.
Given the function
There exists an absolute minimum over the interval