Mobile design became the most significant element as the number of people using their phones to access the internet increased. In 2010, Ethan Marcotte, a brilliant and motivated web designer, changed the way mobile website design was done. Instead of creating a separate mobile site design development, he suggested that the same material be used in different layouts and styles depending on the screen size. Around this time, the phrase "responsive design" was coined.
On a technical level, we still use HTML and CSS, so it's more of a philosophical shift. The most important benefit of Responsive Design is content parity, which implies that the website appears the same no matter where it is viewed.
