The Liskov Substitution Principle (LSP) is an important concept in object-oriented design. It states:

"Objects of a superclass should be replaceable with objects of a subclass without affecting the correctness of the program."

This principle means that a subclass should behave in a way that it can substitute for its parent class without causing issues in the system. If a subclass breaks the behavior expected from the parent class, it violates LSP.