The unsigned keyword is a data type specifier, that makes a variable only represent natural numbers (positive numbers and zero). It can be applied only to the char, short,int and long types. For example, if an int typically holds values from -32768 to 32767, an unsigned int will hold values from 0 to 65535. You can use this specifier when you know that your variable will never need to be negative. For example, if you declared a variable 'myHeight' to hold your height, you could make it unsigned because you know that you would never be negative inches tall.