Where does Moodle store the files that users upload for their assignments?

Imagine that a user uploads a file called "myAssignment.docx" to Moodle to complete the submission of an assignment. Where would the folder containing "myAssignment.docx" be? Is it in the moodledata folder outside the public web directory or somewhere else? I am trying to locate that folder because I want to monitor its growth to determine when I should upgrade my web hosting service to provide more storage space for files that students upload to the server.