They are a pair of congruent and parallel faces of a prism.
prism
A prism
It could be a prism, but need not be. A regular dodecahedron, for example, is not a prism but has parallel and congruent pentagonal bases. You can also have any antiprism (see link).
Look at the prism. If all faces are rectangular (or square) then so are the bases. Otherwise they are the two congruent parallel faces that are not rectangular. Look at the prism. If all faces are rectangular (or square) then so are the bases. Otherwise they are the two congruent parallel faces that are not rectangular. Look at the prism. If all faces are rectangular (or square) then so are the bases. Otherwise they are the two congruent parallel faces that are not rectangular. Look at the prism. If all faces are rectangular (or square) then so are the bases. Otherwise they are the two congruent parallel faces that are not rectangular.
A prism has two congruent parallel bases.
Both a cylinder and a prism can have parallel and congruent bases.
They are a pair of congruent and parallel faces of a prism.
prism
Its "bases"
No
A prism
An upright pentagonal prism has two congruent parallel bases and 15 edges.
It could be a prism, but need not be. A regular dodecahedron, for example, is not a prism but has parallel and congruent pentagonal bases. You can also have any antiprism (see link).
A rectangular prism has congruent bases and parallelograms as lateral surfaces.
prism and cylinder
Look at the prism. If all faces are rectangular (or square) then so are the bases. Otherwise they are the two congruent parallel faces that are not rectangular. Look at the prism. If all faces are rectangular (or square) then so are the bases. Otherwise they are the two congruent parallel faces that are not rectangular. Look at the prism. If all faces are rectangular (or square) then so are the bases. Otherwise they are the two congruent parallel faces that are not rectangular. Look at the prism. If all faces are rectangular (or square) then so are the bases. Otherwise they are the two congruent parallel faces that are not rectangular.