A capital letter is a letter of formal shape.

Capitals were originally derived from the stiff and angular letters used in formal inscriptions.
Originally all writing was done in capitals.

Later the scribes devised less formal shapes for the letters, making use of lines more easily made by brush or pen on papyrus, parchment, or paper.

The capitals were retained for certain uses but the less formal shapes were employed to do the greater part of the work.

These less formal letters have been known by several names.