In order to represent the yes/no nature of condition phrases, we need a special type of value called a Boolean (named after the great logician George Boole). There are only two possible boolean values: true and false (which correspond to "yes" and "no"). These are represented in Snap! by the blocks true and false. Blocks that report true or false are called "predicates."

5 > 3 returns 'true'

These functions represent the yes/no questions we were discussing earlier. Predicate functions in Snap! will always have the pointed, hexagonal shape (like this: a predicate block).

Let's take a look at a few simple predicates that are built in to Snap! Most of these can be found on the green "operators" tab.

Quiz: what does each expression return?

3 + 1 = 4
true
true
3 > 9
true
true