Triangle similarity refers to the concept that two triangles are similar if their corresponding angles are equal and their corresponding sides are in proportion. This means that the shape of the triangles is the same, but their sizes may differ. Similar triangles can be identified using various criteria, such as the Angle-Angle (AA) criterion, where two angles of one triangle are equal to two angles of another triangle. In practical applications, triangle similarity is often used in fields like geometry, trigonometry, and architecture. It allows for the calculation of unknown lengths and angles in a triangle by comparing it to a similar triangle. This principle is essential for solving real-world problems involving scale models and maps.