Philology (from Ancient Greek φιλολογία (philología) 'love of word') is the study of language in oral and written historical sources; it is the intersection of textual criticism, literary criticism, history, and linguistics (with especially strong ties to etymology). Philology is also defined as the study of literary texts as well as oral and written records, the establishment of their authenticity and their original form, and the determination of their meaning. A person who pursues this kind of study is known as a philologist.

In older usage, especially British, philology is more general, covering comparative and historical linguistics.

Classical philology studies classical languages. Classical philology principally originated from the Library of Pergamum and the Library of Alexandria around the fourth century BC, continued by Greeks and Romans throughout the Roman/Byzantine Empire. It was eventually resumed by European scholars of the Renaissance, where it was soon joined by philologies of other European (Germanic, Celtic), Eurasian (Slavistics, etc.), Asian (Arabic, Persian, Sanskrit, Chinese, etc.), and African (Egyptian, Nubian, etc.) languages. Indo-European studies involve the comparative philology of all Indo-European languages.

Philology, with its focus on historical development (diachronic analysis), is contrasted with linguistics due to Ferdinand de Saussure's insistence on the importance of synchronic analysis. While the contrast continued with the emergence of structuralism and the emphasis of Noam Chomsky on syntax, research in historical linguistics often relies on philological materials and findings.