In web design, the term "backend" refers to the non-visible part of a website or web application that is used by administrators or website operators to create, manage and edit content. It is the part of a website that is responsible for the functionality and management of the content and is usually protected by a login page.
A content management system (CMS) such as WordPress is an example of a backend system. It allows users to create, manage and edit content for their website without the need for extensive knowledge of web design or programming. The WordPress backend includes a variety of functions, such as creating and editing pages and posts, managing users and permissions, adding plug-ins and customising the design and layout.
In contrast, the visible part of a website that is accessible to the end user is known as the "frontend". The frontend is the part of a website that the user interacts with and usually consists of HTML, CSS and JavaScript code that is interpreted by a web browser.