Which attribute characterizes an equilateral triangle?

An equilateral triangle is characterized by having three equal sides. This property defines it as a specific type of triangle where not only are all three sides of the same length, but this also leads to all three angles being equal, each measuring 60 degrees. This uniformity in side lengths and angles is what distinguishes equilateral triangles from other types of triangles, such as isosceles triangles, which have two equal sides and two equal angles, or scalene triangles, which have all sides and angles of different measurements. By definition, an equilateral triangle does not possess any sides that are longer or shorter than the others, nor does it have varying angles, as all angles are congruent. Thus, the correct answer highlights the fundamental property that defines an equilateral triangle.