‘ “They don’t speak our language”: identity in linguistics’ considers the relationship between language and identity. For individuals and groups, language has instrumental and symbolic functions, which can be in conflict with each other. The instrumental function of communication stands for inclusion, while the symbolic function of identity manifestation stands for exclusion. Language serves identity manifestation with regard to nation, region, social class, ethnicity (race), gender, and age. The respective linguistic differences can be highlighted or downplayed. Yet, on the level of individual expression in both speech and writing, language has biometric qualities allowing for highly reliable speaker identification.