Parallel planes are planes that do not intersect or meet. Take a look at the following figure. The figure shows two planes that are parallel.
Notice that you can extend these two planes as much as you wish. However, they will never meet.
Use the diagram below in order to find all pairs of parallel planes.
Plane ABFE is parallel to plane DCGH
Plane AEHD is parallel to plane BFGC
Plane ABCD is parallel to plane EFGH
As you can see from this example, a box or rectangular prism will always have three pairs of parallel planes.
A plane and a line that do not intersect are also parallel. In the figure above, plane EFGH is parallel to line AB. By the same token, plane BFGC is parallel to line DH