The first language a person learns is known as their native language and is usually a major part of their identity, shaping their earliest thoughts and connecting them with their culture and heritage.

After moving abroad, I found my English slowly eroding. It turns out our first languages aren’t as embedded as we think. Credit...Artwork by PABLO DELCÁN Supported by By Madeleine Schwartz Madeleine ...

Almost half of all people in the world today speak an Indo-European language, one whose origins go back thousands of years to a single mother tongue. Languages as different as English, Russian, ...