As an instructor, Speed Grader allows you to view and grade student assignment submissions in one place using a simple point scale or complex rubric. Canvas accepts a variety of document formats and even URLs as assignment submissions. Some document assignments can be marked up for feedback directly within the submission. You can also provide feedback to your students with text or media comments.
You can access SpeedGrader through: Assignments, Quizzes, Graded Discussions, and Gradebook
How do I get to SpeedGrader from the Gradebook?
How do I add annotated comments in student submissions using DocViewer in SpeedGrader?