Certificates are awarded for completing paths such as the Web Development Path (Ruby on Rails). When you go to a path, you will see a certificate section that will be locked if you have not cleared all checkpoints. Once you clear all checkpoints of that path, you will have completed it and the certificate will become available for download.

Please note that certificates are not awarded for completing all lessons of a course (ie. all lessons in HTML & CSS), as new lessons may be added to courses in the future.