Integers (Ints) are whole numbers, such as 32 and −100. Integers are useful when you need to perform calculations (that is, adding, subtracting, multiplication, and so on). Let's add some numbers to Playgrounds. On the next line, under your name, type 32, and then, on the following line, −100, as demonstrated in the following screenshot:

Again, you see both 32 and −100 in the Results Panel under your name.