Frontend or Front-end or FE is a front-facing layer or application. It can be many things.

It can be:

• Facebook mobile app
• A user-facing application (website, mobile app)
• A client that connects to a backend or server
• An admin website that connects to a backend but the end-user will never see
• Anything that the user can interact directly
• Etc.

When people say frontend most of the time it's a user-facing application.

Let's think about a restaurant. They have a front-facing restaurant and a kitchen. The front-facing restaurant where guests can sit and enjoy their meals is the frontend.