Templates are PHP files that are used to generate pages or parts of pages requested by blog visitors. Let’s take a look at the different options for templates that can be used as part of a theme.
WordPress allows you to define separate templates for different needs and parts of your blog, but it is not at all necessary that all of these different templates for your blog be executed simultaneously to generate pages in their entirety. Templates are selected and used to generate a page based on a hierarchy of templates, depending on which templates are available in a particular theme. As a theme developer, you can choose the number of customizations you want to implement using templates. For example, as a last resort, you can use just one template file, named index.php as the template for all pages created and displayed on the blog. However, it is most common to use different template files to generate different kinds of pages to allow for maximum customization flexibility.
Basic Templates.
A minimal WordPress theme consists of two files:
style.css.
index.php
Both of these files are placed in the theme folder. The index.php template file is very flexible. It can be used so that it adds all the links to the header, sidebar, footer, content, categories, archives, search, error pages and other necessary web pages created by the user on your site. In another theme build option, develop other modular template files for the theme, each of which will take over some of the functionality.
If you don’t add your own template files to the theme, WordPress will use the default built-in template files. For example, if you don’t have template files in your theme: neither comments.php nor comments-popup.php, WordPress will automatically use the default wp-comments.php and wp-comments-popup.php template files, according to the Template Hierarchy. These default templates probably won’t match your theme styles, so you’ll probably have to develop your own template files. Here are the basic files that are commonly used to separate page views (and should be in your theme directory):
header.php
sidebar.php
footer.php
comments.php
comments-popup.php
If you’ve developed these modular template files, you can add them to index.php (the main template file) and the result will appear on the user’s page. To enable or get these template modules where you want them, follow the instructions.
To add a header.php template, use the get_header() template tag.
To add a sidebar.php template, use get_sidebar() template tag.
To add a footer.php template, use the get_footer() template tag.
For more information on how to develop different templates and how they work, and how to generate different information in them, see the Templates documentation.