Learn in the textbookFeedback Display and Web Design Implementation
DefinitionMobile first (モバイルファースト) is a policy of thinking first about ease of use on small-screen mobile devices such as smartphones when designing a website or similar.
ExplanationThe design starts by deciding what goes on the small screen and then widens the display for devices with larger screens. A narrow screen operated by finger forces you to trim the information and make tappable areas large, so those limits become the starting point of the design.
AnalogyIt is like deciding first what goes in a small travel bag, so that with a big suitcase you only need to add things.
Memory hookFirst means at the very start. Read it as putting the small mobile screen on the design desk before anything else.