Which language is primarily used to set the structure of web content?

The primary language used to set the structure of web content is HTML, which stands for HyperText Markup Language. HTML is designed to organize and display content on the web by using a series of elements or tags that define different parts of the content. For instance, HTML tags are used to create headings, paragraphs, lists, links, images, and other types of content.

The structure established by HTML is essential because it lays the foundational framework for how content is presented in a web browser. This structural aspect allows browsers to interpret and render the elements on a web page correctly. Without HTML, there would be no organized way to define and display the content users see on websites.

While CSS (Cascading Style Sheets) is important for styling and visually enhancing HTML content, its role is to determine how the HTML elements should look, such as layout, colors, fonts, and overall appearance. JavaScript is primarily used to add interactivity and dynamic functionality to a website. PHP is a server-side scripting language typically used for back-end development and does not define the structure of web content directly. Therefore, HTML is unequivocally the correct answer for establishing the web content structure.