This document provides an introduction and overview of UI (user interface) and UX (user experience). It defines UI as the medium for interaction and information exchange between a system and user, focusing on usability. It defines UX as involving a person's behaviors, attitudes, and emotions when using a product or service, including the actual experience, usability, and meaningfulness of human-computer interaction. The document then discusses some UX design trends and methods, positioning UX as focusing on the needs of people and coming before UI in the design process.