An inherent vowel is part of an abugida (or alphasyllabary) script. It is a vowel sound which is used with each unmarked or basic consonant symbol.
There are many known abugida scripts, including most of the Brahmic scripts and Kharosthi, the cursive Meroitic script, which developed in Nubia (today in Southern Egypt and Northern Sudan), and the Ge'ez script. Many of them are still used today. Old Persian cuneiform also uses a device similar to an inherent vowel, though only with a subset of its consonants, so some authors do not consider it to be a true abugida. Although it is the earliest known script to use the inherent vowel principle (from the 6th century BC), no direct link among these four writing traditions has yet been demonstrated.