Draftback is a Google Docs add-on that plays a time-lapse video of how a document was assembled. It shows each keystroke, illuminating the user's process. It can be a useful tool for reviewing a student's writing proficiency or how a group worked together to create a final product.
Draftback is most frequently used to identify when users copy and paste text into a document. If that text is not cited appropriately, that recorded action could be evidence of plagiarism. Draftback can also be used to identify who has worked on a document and when each person made changes. (You can easily track who has accessed a document in Google, but contribution is a little trickier.)