A person's second language, or L2, is a language that is not the native language (first language or L1) of the speaker, but is learned later (usually as a foreign language, but it can be another language used in the speaker's home country). A speaker's dominant language, which is the language a speaker uses most or is most comfortable with, is not necessarily the speaker's first language. The second language can also be the dominant one. For example, the Canadian census defines first language for its purposes as "the first language learned in childhood and still spoken", recognizing that for some, the earliest language may be lost, a process known as language attrition. This can happen when young children move to a new language environment.