SOLID Design Principles - Definitions

Interface Segregation Principle

Clients should not be forced to depend on interfaces they don't use, favoring many specific interfaces over one general-purpose interface

Single Reponsibility Principle

A module should only have one responsibility

Open/Closed Principle

Software should be open for extension, but closed for modification

Liskov Substitution Principle

Objects of a superclass should be replacable with objects of a subclass without affecting program correctness

Dependency Inversion Principle

Law of Demeter

A method should only call methods of its own object, objects passed as parameters, objects it creates, or objects in instance variables, avoiding "train wreck" chains of method calls.