"Responsive web design" is not a technology, product or a programming language. Rather, it is an "approach" to the design and development of web content wherein through the use of certain techniques (such as, but not necessarily limited to CSS and Media Queries), an HTML page is made to "respond" to changes in screen size and resolution by adapting the contents to better fit the screen. This may involve changing the properties of elements as the screen get smaller, removing the elements alltogether, or replacing the elements with different implementations.