A quadrilateral is a four-sided figure in 2-dimensional space made up of four line segments. In Euclidean plane geometry, a quadrilateral is a polygon with four edges (or sides) and four vertices or corners. Sometimes, the term quadrangle is used, by analogy with triangle, and sometimes tetragon for consistency with pentagon (5-sided), hexagon (6-sided) and so on. The most common types of quadrilaterals are Squares and Rectangles. The seven types of quadrilaterals are parallelogram, rhombus, kite, rectangle, trapezoid, square, and isosceles trapezoid.
Chapter 17 "Special types of Quadrilaterals" student will get to know about different types of quadrilaterals, its properties, and formulas to solve the problems, etc. The concepts were explained beautifully in a detailed manner, along with suitable examples wherever it's needed.