A mechanical pencil (U.S. English) or a propelling pencil (UK English) is a writing tool with a replaceable and mechanically extendable pigmented core, otherwise known as "lead." It may be used for convenience as the lead does not require sharpening and can be extended each time the lead becomes short. Some artists prefer its constant thickness leading to better accuracy.
Overview
Since the pencil's grip is separate from the lead, the pencil doesn't shorten like conventional pencils do when sharpened over time. The lead is easily replaced as mechanical pencils have compartments to hold the lead. Artists may like feeling of holding a mechanical pencil with a preferred grip while having the choice to insert leads of different hardness or color. The first popular mechanical pencil in Japan was a screw-based pencil called "Ever-Ready Sharp Pencil"-- its success later became the name of the company we know today as "Sharp." At the same time, a ratchet-based mechanical pencil was being developed in the United States. These two mechanical pencil designs are the precursor to many in use today.
Many will omit "mechanical" when describing this writing tool as it has slowly overcome the previously widely used wooden barrel-cased pencil in popularity.
In some countries, especially in Japan and South-Korea, a mechanical pencil may be known as a "Sharp Pencil" due to becoming a genericized trademark--similar to how we may call a photocopy a "Xerox" and when we search, we "Google" it.
