xkcd xkcd.com xkcd.com: A webcomic of romance and math humor.Phase Changeson September 19, 2025 at 04:00 Question Markon September 17, 2025 at 04:00 -Style Pizzaon September 15, 2025 at 04:00 Mantle Modelon September 12, 2025 at 04:00 Phase ChangesQuestion Mark-Style PizzaMantle Model