This tutorial presents a unique combination of instruction to Roofline by its creator, hands-on instruction in using Roofline within Intel and NVIDIA production performance tools by Intel and NVIDIA staff, and discussions of real-world Roofline use cases at ALCF, NERSC and INESC-ID computing centers. The tutorial presenters have a long history of collaborating on the Roofline model and have presented several Roofline-­based tutorials.