Examples :

if you need to keep track of which floor you are in, where:

• you may have negative floors (underground);
• you don't expect to go more than 32767 floors...

you can declare a variable "floor":

int floor;

if you want to keep track of how many students are enrolled in school and:

• you do not have a negative number there;
• there is a chance you have more than 32000 but not more than 64000;

you can declare a variable "students":

unsigned int number_of_students;