Integers are formed by natural numbers (positive whole numbers, eg. 1,2,3,4), and also formed by the negative whole numbers (eg.-1,-2,-3,-4). All in all, they are numbers that can be written without being in a fraction or with decimals (eg. 50,24,-80).
Integers are expressed on a number line, which will go on forever, and 0(zero) being in the centre. Integers on its left will be negative, while those on its right will be positive. Absolute values of an integer is always positive and written with "|" on the number's sides (eg. |2|).