* H stands for hard. Harder leads produce lighter lines and are typically used for technical drawing, sketching, and writing.
* B stands for black. Softer leads produce darker lines and are typically used for shading, drawing, and sketching.
The number following the letter indicates the degree of hardness or blackness. For example, a 9H pencil is very hard and light, while a 9B pencil is very soft and dark. HB is a middle ground, being neither very hard nor very soft.