When 2 lines are cut by a transversal, eight different angles are created, four around each point of intersection. The angles can be described as interior or exterior depending on where they are located. Interior angles lie between the lines being intersected, while exterior angles lie outside.

Consecutive angles are angles that lie on the same side of a transversal. Consecutive interior angles are the angles that lie inside the intersected lines and on the same side of the transversal.

In the figure above, there are two pairs of consecutive interior angles. $$\begin{array}{c}\angle 3\text{and}\angle 6\\ \angle 4\text{and}\angle 5\end{array}$$