Burnt Bit is a term used to describe the residue left behind after a fire. It is usually composed of charred wood, ASH, and other materials that have been burned. The term 'burnt bit' is derived from the Old English word 'bryntbitu, ' which means 'burnt piece.' ASH, with three letters, is the residue left behind after something has been burned. It is usually a fine, powdery substance that is made up of minerals and other elements.