The History of Letter Case: From Majuscule to Minuscule
Roman inscriptions used only what we now call uppercase — the "majuscule" forms. Lowercase letters ("minuscule") emerged in the medieval period as scribes sought faster, more compact scripts. The Carolingian minuscule of the 8th century is the ancestor of every lowercase letter we use today.
The terms "uppercase" and "lowercase" come from the physical typesetter's case — capital letters were stored in the upper drawer, small letters in the lower. The language of print outlived movable type itself.