Relative extrema, or relative minimums and maximums of a function, or of its graph, are points in its domain (where it's graph exists) where the function has the highest or lowest value for a small region around that point.
For example, the following graph has relative extrema at x = 0.11 and x = 1
Relative extrema of a function can be calculated by the help of its critical points. This is because the relative extrema always exist only at critical points. That is, only a critical point of a function can be its relative maximum or minimum
Critical points need to be classified as relative minimums and maximums. There are three ways to do this:
Check function's value at and between the critical points