A prototype is a simulation or sample version of a final product, which is used for testing prior to launch. The goal of a prototype is to test products (or product ideas) before spending lots of time and money into the final product.

A visual guide that represents the page structure, as well as its hierarchy and key elements. Wireframes are useful when UX designers need to discuss ideas with team members/stakeholders, and to assist the work of visual designers and developers.

Sketching is a quick way of visualizing an idea (e.g. new interface design) by using paper and pen. Sketches are useful to validate product concepts and design approaches both with team members and users.