Responsive Web Design (abbreviated RWD and sometimes referred to simply as responsive design) is the most common name given to a collection of techniques and technologies used to adjust the layout and features of a website to meet the needs of the particular context (generally assumed to be the device type) in which it is being presented. This allows producers to create a single code base and point of entry for all visitors. Although RWD is the name generally used, other terms have been used to describe similar or related techniques. These terms include fluid web design, liquid web design, reactive web design, and adaptive web design. Many of these terms are still in use, but RWD is quickly becoming the catch-all term for user-centered contextual design. Combined with a progressive enhancement design philosophy—which emphasizes that sites do not have to look exactly the same across all platforms on all browsers, but must simply be accessible by them—RWD is used to create sites that can be automatically scaled and reconfigured based on the capabilities of the platform. This allows optimization of the presentation with minimal extra production work. With an increasing number of website visitors using smartphone and tablet devices, RWD is seen as the best strategy for ensuring these audiences' needs are met with minimal extra production or development work.

This section can be used to understand how current sites can begin to migrate to the new format on a wider variety of platforms (and devices), or work with vendors to develop solutions for new sites. Responsive web design guidelines have been broadly categorized in this section under:

• How responsive web design works
• Evaluating sites for responsive web design
• Creating responsive sites and content
• Client-side and server-side techniques
• Best practices