Object-oriented programming (OOP) focuses on organizing code around objects that encapsulate data and behavior, contrasting with structural programming, which emphasizes functions and data as separate entities. Key concepts in OOP include encapsulation, inheritance, and polymorphism, which facilitate code organization and reuse. Methods in OOP can operate on an object's internal data without requiring external input parameters, as they inherently have access to the object's properties. Abstraction in OOP simplifies user interaction by hiding complex internal details, allowing for easier modifications. Understanding these principles is crucial for effectively utilizing OOP in programming tasks.