A quadrilateral is a four-sided polygon. There are irregular and regular quadrilaterals.
A type of special quadrilateral is a rectangle. A rectangle is a quadrilateral with four right angles.
A rhombus is another special quadrilateral. A rhombus is a quadrilateral with four congruent sides.
A square is a quadrilateral with four right angles and four congruent sides.
Since these parallelograms are considered special, it is good to note that they have different sets of theorems and postulates that come with them.
A kite is a quadrilateral with exactly two pairs of congruent consecutive sides.
A trapezoid is a quadrilateral with exactly one pair of parallel sides. Each of the parallel sides is called a base. The nonparallel sides are called legs. Base angles of a trapezoid are two consecutive angles whose common side is a base.
The midsegment of a trapezoid is the segment whose endpoints are the midpoints of the legs.
Holt Geometry Book