This is a difficult question, and I’m sure everyone has their own little definition, but I think it’s something we need to be explicit about somewhere.
The DDH page purporting to answer this question gives a useful account for those wanting to know about the Department and its history in the discipline, but if they’re looking for a beginner’s definition of DH itself, it studiously doesn’t answer the question. The Wikipedia article on the subject does offer a concise definition, which is probably useful for a beginner, but I’m sure we could all pick holes in it or object to some of the language used.
Can we do better? (In a couple of sentences!)
To get the ball rolling, here’s my attempt:
Digital Humanities may involve the application of methodologies and research agendas from computer science and other informatics-heavy sciences to the subject area of traditional humanities disciplines, such as literature, history and languages.