A quadrilateral has four sides and four vertices. It can be either convex or concave. When all the sides are equal, it becomes a square. A rectangle is a special type of quadrilateral where all the sides are right angles. Did you know that the sum of the interior angles of a quadrilateral is always 360 degrees?

Convex Quadrilateral – In a convex quadrilateral, all four sides are visible from one point inside the shape. It means that if you stand at one corner, you can see all other three corners without any obstruction. Isn't that cool?

Concave Quadrilateral – In a concave quadrilateral, there is at least one side that is not a straight line. You can think of it like this: imagine a quadrant (a quarter circle) with two opposite edges extended to form a line segment. That would give you a concave quadrilateral. Now, imagine holding the shape in your hands and bending it slightly so that one edge becomes curved instead of straight. That's what makes it concave!