User interface (UI) design patterns are ready solutions for recurring design problems. Those patterns come in form of UI Components. To exemplify, Captcha is a component that enables a strong verification of the data origin and makes sure it comes from a human and not a robot.

Design patterns are the standard reference point for experienced user interface designers. They provide a common language for designers that could save time and improve collaboration by boosting communication since mentioning a design pattern’s name implicitly express much more details than just the name.

Source:

Design patterns,http://ui-patterns.com/patterns