Andrew Stuart "Andy" Tanenbaum (sometimes referred to by the handle ast) (born March 16, 1944) is a professor of computer science at the Vrije Universiteit, Amsterdam in the Netherlands. He is best known as the author of MINIX, a free Unix-like operating system for teaching purposes, and for his computer science textbooks, regarded as standard texts in the field. He regards his teaching job as his most important work.