The term "90°" refers to a right angle, which is a fundamental concept in geometry. A right angle measures exactly ninety degrees and is commonly represented by a small square in diagrams. It is formed when two lines intersect at this angle, creating a corner that is neither acute (less than 90°) nor obtuse (more than 90°). In practical applications, 90° angles are essential in various fields, including architecture, engineering, and carpentry. They help ensure structures are built correctly and maintain stability. Tools like protractors and set squares are often used to measure and create right angles in construction and design.