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. A second language may be a neighboring language, another language of the speaker's home country, or a foreign language. 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. 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 start school or move to a new language environment.