It's part of the course URL when you're enrolled at the course home, e.g: https://class.coursera.org/algs4partI-010 -> algs4partI-010 https://www.coursera.

It's part of the course URL when you're enrolled at the course home, e.g: https://class.coursera.org/algs4partI-010 -> algs4partI-010 https://www.coursera.org/learn/machine-learning/home/welcome -> machine-learning (see https://github.com/coursera-dl/coursera-dl/wiki https://github.com/coursera-dl/coursera-dl/wiki)