According to angles:
1) Right triangle = with a 90-degree angle
2) Acute triangle = with distinct acute angles, but no right angle (acute angle measures less than 90 degrees)
3) Obtuse Triangle = with one obtuse angle (angle whose measure is more than 90 degrees but less than 180 degrees)
4) Equiangular triangle = all angles have equal measurements.
According to sides:
1) Equilateral triangle = all sides are equal in measure.
2) Isosceles triangle = Two sides are equal.
3) Scalene triangle = each side has different measurement.