While people having skills in HTML and other web scripting languages can opt for designing their own site it is not a viable choice for everyone. Some of the web designers use pre defined and readymade web templates for quick and effective site designing.
We might divide a page template into a header, content, sidebar and footer where these are in separate files. The content will change most between pages, so rather than having a content file, we include the content into a page file which pulls in the individual template files and defines the unique features of that page. The unique features of a page will be the title, description and article content. We can define these at the start of the page template with say PHP code to set the value of variables that are used by the other templates such as the header template. Then we assemble the page by including the required templates and inserting the content.