Adjacent angles are two angles that share a common vertex and a common side but do not overlap. They are positioned next to each other, making them easy to identify in geometric figures. For example, if two angles are formed by two intersecting lines, the angles that are next to each other at the intersection are considered adjacent angles. In geometry, adjacent angles can be useful in various calculations and proofs. They can be added together to find the measure of larger angles, especially when dealing with straight lines or polygons. Understanding adjacent angles is essential for studying other concepts in geometry and trigonometry.