original_query: What is grammaticalization in historical linguistics?
query: What is grammaticalization in historical linguistics?
answer: Grammaticalization is a process of language change where words representing objects and actions (nouns and verbs) become grammatical markers (affixes, prepositions, etc.).  It creates new function words from content words, as seen in the evolution of the Old English verb 'willan' into the Modern English auxiliary verb 'will'.