What is the past-the-end iterator in STL C++?

Question

Any one could explain me what is the meaning of past-the-end. Why we call end() function past-the-end?

Answer 1

Adding another point to the above correct answers. This was also done to be compatible with arrays. For example in the code below:

char arr[5];
strcpy(arr, "eakgl");
sort(&arr[0], &arr[5]);

This will work fine.

Instead if you had given :

sort(&arr[0], &arr[4]);

it would miss sorting the last character.

This also helps to represent empty containers naturally.