A circular saw is a hand-held power tool, largely used for crosscutting and ripping wood, and for cutting various materials to length and width.  They are capable of cutting a wide variety of materials, including wood, steel, masonry and ceramic tile.  Cordless types of circular saws are convenient for working in areas with limited space, however, the corded varieties provide more power and are better suited to the harder materials such as stone and ceramic tile.

Video: How to Operate a Circular Saw