If three sides of one triangle are equal to three sides of another triangle, then the two triangles are congruent by the __________ criterion.

Concept: SSS criterion is an abbreviation for Side-Side-Side criterion.

Two triangles are congruent if three of their sides are equal to the corresponding sides of the other triangle.

Because all three corresponding sides of the triangles are equal, they are congruent according to the SSS rule of congruence.