SSS
Side
Side
Side
These are how you know if the sides are all congruent. You will now because the numbers would be the same on each and every side of the triangles.
SAS
Side
Angle
Side
These set is also how you can figure out it is congruent on the side, then angle, then side again. You will know because all the sides and the angle will be the same as the other triangle.
ASA
Angle
Side
Angle
The third set of the finding out if the triangles are all congruent. You will know because all the angles and the one side would be the same as the other.
AAS
Angle
Angle
Side
The fourth set of finding out the triangles are all congruent. You will know because all the angles and the one side would be the same as one of the other sides.
HL
Hypotenuse
Leg
The last set of finding out the triangles are all congruent. You will know because all the angles and the one side would be the same as one of the other angles.