What are the boundary lines in soccer?

There are a number of lines on a soccer field. None of them are called boundary lines. The touch lines run up and down the length. They form the sides. The goal lines are across the ends of the field. The touch lines and goal lines define the field's perimeter or its boundary. And a ball that is in play must wholely cross one of these lines (either on the ground or in the air) to be considered out of play.