Two figures are similar figures if there is a composition of transformations that maps one figure onto the other. In other words, two figures are similar if they have the same shape and the ratios of their corresponding linear measures are equal. To denote algebraically that two figures are similar, the symbol $\sim$ is used. When writing a similarity statement, the corresponding vertices must be listed in the same order. For the polygons above, two of the possible similarity statements can be written as follows. The same definition is applicable to three-dimensional shapes. For the polyhedrons above, one of the possible similarity statements is shown below.

Among two-dimensional figures, all squares are similar and all circles are similar. Similarly, for $3\text{D}$ figures, all cubes are similar and all spheres are similar.