Kenneth C. Zirkel · CC BY-SA 3.0

Liskov's work gave programmers the conceptual tools that much of modern software still runs on: abstract data types, formalized data abstraction, and the Liskov substitution principle, which defines when one type of object can safely stand in for another in object-oriented code. That 2008 body of work won her the Turing Award, computer science's highest honor, making her only the second woman to receive it after having already been among the first women in the United States to earn a doctorate in the field.