The document discusses the evolution and significance of responsive web design, introduced by Ethan Marcotte in 2010, which allows websites to adapt to various screen sizes and orientations. It emphasizes the benefits of responsive design, including improved user experience, SEO advantages, and cost efficiency by eliminating the need for multiple site versions. With increasing device usage, particularly smartphones and tablets, the document asserts that 2013 marks a pivotal year for implementing responsive design in web development.