How does the Grade Book work in Canvas?

Using the Gradebook:

The Canvas Gradebook is a fully featured management tool that allows instructors to:

Simultaneously view grade information across all courses.
Be notified when assignments submitted.
Notify students when an assignment has been graded.
View Grade history and revert updated assignment scores to previous scores.
Download or upload Grades as a CSV file.
Utilize offline grading capability by downloading assignment submissions into a zip file and upload when connectivity is available.
Block students from viewing their grades until they are published.
Create custom weighting and grade ranges.
View a report of all historical grade changes.
Message students whom haven't submitted an assignment yet.
Message students who scored more than X or less than Y on an assignment.
Leave private grading notes/comments for the student.