The page curl effect is a graphical technique used in digital applications, often seen in e-book readers or image viewers. It mimics the behavior of turning a physical page in a book, where one corner of the page appears to curl as you drag it, revealing the content on the next page beneath. This effect adds a realistic and engaging visual element to digital interfaces, providing a tactile sense of interaction. It's achieved through a combination of 2D graphics, shading, and animation techniques.