What is Frontend
The part of an application people see and touch: the screens, buttons, and forms running in a browser or on a phone.
In plain terms
Frontend code runs on the user's own device, usually inside a web browser. Frontend developers turn designs into working screens and make them fast, accessible, and correct at every size. The core tools are JavaScript or TypeScript plus a framework, with React the most common by a wide margin.
What it tells you about a developer
Strong frontend developers pair engineering with product sense: they notice a 100-millisecond delay and work closely with designers. Expect depth in React or a peer framework. Performance and accessibility work marks the senior end of the discipline, and it carries across every frontend job.