Shadows of Sanctuary
Common is a language spoken by most sapient creatures. It was originally designed to be a trade language, and was constructed by Miralithen historians from bits and pieces of Elderspeak, with common phrases and language conventions borrowed from many other languages around the world, mostly Miralithi.
The common tongue is very young, only 150 years old. In modern times, many people learn it as their first language. The Miralithi language, for example, is already nearly extinct, as most of the humans of the Giant's Steps learn Common as children and never learn their ancestral tongue.