A right angle is the square corner you see everywhere around you: where two walls meet, at the corner of a book, or where the edges of a window frame join together. When two lines meet to form a right angle, they're perpendicular to each other, creating that perfect L-shape.

Right angles measure exactly 90 degrees. If you imagine a full circle divided into four equal parts, each part would be a right angle. Mathematicians often mark right angles with a small square in the corner to show that it's exactly 90 degrees, distinguishing it from other angles.

Right angles are fundamental to building and construction. When carpenters check that a wall stands at a right angle to the floor, they're making sure the building will be stable and square. The corners of most rooms, tables, and buildings use right angles because they create strong, predictable structures. Even your computer or tablet screen has four right angles at its corners.

The word “right” here doesn't mean “correct,” though right angles are certainly the right choice for many building projects! When something is at a right angle to the ground, it stands straight up, perfectly vertical.