Perusall is a social annotation tool that allows students and their instructors to collaboratively markup .pdf documents. Instead of reading a document and discussing it, Perusall brings the discussion to the text. Other functionality includes question annotations, annotation filtering, support for automated grading, and analytics.
With Perusall, the professor is able to assign textbooks, articles, and pdfs that the students can access easier than they would without Perusall. Students are then able to annotate the readings, comment, on the readings, question something from the readings, and respond to comments and questions that other students have posted. Perusall also has a built in algorithm that keeps track of subjects with many clarifications as well as students who are struggling in class.
The Perusall tool is now available in Canvas both as a course navigation link and as an external tool when setting up an assignment (assignment links enable grade sync).
See the Perusall support site for more complete information about how and why you would use one over the other:
.....(ignore the first couple of paragraphs about adding the tool to Canvas -- that has already been done.)
For more general information about the Perusall tool, go to the main Perusall support page:
.....(note the links to pages targeted for instructors and students.)