A sphere does have a surface and volume, and all we need to know to calculate the volume and surface area of a sphere is the measure of its radius! Now, just like with a circle, we can divide a sphere in half. Half a sphere is called a hemisphere, and it has precisely one-half the volume of the entire sphere. A sphere is a perfectly round geometrical 3-dimensional object. It can be characterized as the set of all points located distance r (radius) away from a given point (centre). It is mainly a three-dimensional object which has volume and surface area. Sphere, the section of a sphere by a plane, surface area and volume are the main concepts discussed in brief under this chapter.