Which type of triangle has exactly two equal sides?

A triangle with exactly two equal sides is classified as an isosceles triangle. This type of triangle is defined by its side lengths, where at least two sides are of equal length, and the angles opposite those sides are also equal. This unique property allows isosceles triangles to have distinct characteristics, such as symmetry about the axis that bisects the angle opposite the base.

In context, scalene triangles are defined by having all sides of different lengths, equilateral triangles have all three sides equal, and right triangles can have varying side lengths, including the possibility of being scalene or isosceles. However, the defining condition for an isosceles triangle is that it must have exactly two sides of equal length, making it the correct choice for this question.