← DictionaryMobile-First
also called mobile first design
Designing the mobile experience first, then expanding to larger screens.
Design the phone version first, because most people are on one.
What It Is
You will find Mobile-First in the Website layer, alongside the rest of Layout. In practice it means this: designing the mobile experience first, then expanding to larger screens.
It is an idea you reason with rather than a deliverable you hand over, so two teams can both hold it correctly and still apply it differently. Once it is defined that clearly, arguments about it usually stop.
How It's Used
You will usually meet Mobile-First in site builds, page structure and the technical decisions underneath them. It normally appears alongside Responsive Design, Breakpoint and Viewport. The practical test is whether a decision changes because of it.
Why It Matters
Mobile-First is cheap to get right early and awkward to fix late. When it is unclear, the site still launches — it just quietly underperforms. Clarity here removes a surprising amount of downstream argument.
Think of it as a lens. Look through it and some choices get obvious. Design the phone version first, because most people are on one.
Termshift™
How the meaning shifts depending on who is using it, and where.
Professionally, Mobile-First carries the narrow meaning: designing the mobile experience first, then expanding to larger screens.
Explained to someone with no marketing background, Mobile-First is design the phone version first, because most people are on one.
The Bottom Line
If you only keep one thing about Mobile-First: design the phone version first, because most people are on one. Everything after that is detail.