Your first language is usually the language you learned and spoke in the home. It can also be your primary language, especially if you've later learned a second language. Your primary language is the language that you speak everyday in most situations — home, work, school, etc. It can be a second language for you. As an example, I'm Deaf and unlike most Deaf people, I learned to speak English as a child and it is still the language I am most fluent in.