Common Tongue

Common is a commercial language that arose in response to increased colonization during the Age of Seafaring. When Mithlerien's enormous navy underpinned a global commerce system in the 700s, it grew to virtually universal use. Almost every sentient, civilized being knows a sprinkling of it, and the majority of them can speak it fluently. While most individuals cannot read or write the language, the people of Valine can communicate with one another in it.
Common is essentially a trade language, which means it isn't appropriate for discussing complex issues. It's a simple language that's not very expressive.
Nearly everyone on Valine's surface speaks Common as a second language. Those who live in isolated locations speak it poorly, but the majority of people can get by.
Although dialects differ from place to region, communication is generally possible. Naawasy is a melodic dialect spoken in Upreye, whereas Geizboni is an Eaqaalan variety and Enniusoshi is spoken in Xeflia, among thousands of other dialects of the Common Tongue.
Linguists refer to the common language spoken throughout Valine as Grocuaqati. Grocuaqati is primarily spoken in eastern Fea, from Gugaon in the north to Matsusaki in the south, and from Saratau in the east to Gamandal in the west, in its purest form.
In other domains, "common" can mean something quite different; these aren't dialects, but rather languages. The dwellers of the Undervale , for example, speak a dialect known as Undercommon. The Feywild dwellers also speak an unique form of "Common."