This chapter introduces the study of language ideologies and the relationship between language, social belonging, and social order, particularly in the context of late modernity. It approaches linguistic categories as discursively constructed rather than naturally occurring. This frames language as a key lens for understanding human social organisation, emphasising that ideas about language reflect and co-construct broader social and political ideologies. Through a discussion of sociolinguistic and linguistic anthropological theories, the chapter critiques essentialist views of language. It introduces concepts such as social indexicality, standard language, prestige, and centring institutions to explore how language acquires social meaning and status. The chapter also examines the material dimensions of language, including the role of writing, sound, and tangible artefacts such as grammars and dictionaries in shaping linguistic ideologies and language categories. It lays the foundations for understanding languages as dynamic, constructed phenomena embedded in specific historical, cultural, and material contexts.