Which technology is essential for building the structure of a website?

The correct choice, HTML, is foundational for creating the structure of a website. HTML, which stands for HyperText Markup Language, provides the basic building blocks that define the elements of a webpage, such as headings, paragraphs, links, images, and other content. It acts as the skeleton that organizes and presents information in a web browser.

While CSS (Cascading Style Sheets) is crucial for styling and layout, and JavaScript enables interactivity and dynamic content, they both rely on HTML for the structural framework. PHP is a server-side scripting language that is typically used for creating dynamic web applications and server interactions, but it does not directly contribute to the basic layout or structure of a webpage.

In summary, HTML is essential for establishing the core structure, making it the primary technology for this aspect of web design.