Pencil lead is the core material found in pencils, primarily made of a mixture of graphite and clay. Graphite is a form of carbon that allows for smooth writing and drawing, while clay helps to bind the graphite particles together and influences the hardness of the lead. The ratio of graphite to clay determines the pencil's hardness, with more graphite resulting in softer leads and less graphite yielding harder leads. The term "pencil lead" is a bit of a misnomer, as it does not contain any actual lead metal. The use of the word "lead" dates back to the early days of writing instruments when a similar material was used. Today, pencils are graded on a scale from H (hard) to B (black), with HB being a common middle ground used for general writing and drawing.