What type of triangle has all sides of different lengths?

A triangle with all sides of different lengths is classified as a scalene triangle. This is because scalene triangles do not have any congruent sides, meaning each side has a unique length.

In contrast, an equilateral triangle has all three sides that are exactly the same length, which is not the case here. An isosceles triangle is characterized by having at least two sides of equal length, again differing from the requirement of having all sides be different. A right triangle refers to the presence of a 90-degree angle, which does not dictate the lengths of its sides and can include both equal and unequal lengths, so it doesn't fit the definition being asked.

Thus, the correct classification for a triangle with all sides of different lengths is indeed scalene.