A circle is a shape consisting of all points in a plane that are a given distance from a given point, the centre; equivalently it is the curve traced out by a point that moves in a plane so that its distance from a given point is constant. We come across various objects in our daily lives which remind us of a circle. Some of the examples of a circle are the wheel, coin, full moon, bangles, tyres etc. The central concepts which are explained in this chapter are angles, chords, arcs, segments and sectors.