A boolean variable is just like any other variable (like an 'int' variable). Except whereas an int variable can hold a lot of different values - 0, 1, 2, 3, 1000, -1, etc - a boolean variable can only have two possible values, 'true' and 'false'. There's nothing magic about them otherwise - they work exactly as other variables do. Because the value of a boolean is already true or false, you don't need to compare them in 'if' statements, i.e. instead of writing: you can write: The program doesn't know what the variable means. The only way your program can behave differently depending on the value of a variable is to use the variable (eg use it an "if" statement as per example above). I'm guessing that your 'turnLeft', 'turnRight' and 'move' methods respond to the value of the checkTreeRight variable in exactly this way.