To fully grasp WordPress themes, you must understand two primary concepts:
A permalink is a permanent, non-changing URL (or link, to a specific resource. For instance:
When a user requests a URL, WordPress reverse-engineers the permalink to figure out which template should control its layout. WordPress looks for the various template files that could control this particular piece of content, and ultimately gives preference to the most specific one it finds. This is known as the Template Hierarchy.
Once WP finds the matching view template in the hierarchy, it uses that file to process and render the page.
index.php (the default, "catch-all" template) will be overridden by
archive.php (the default template for list-based content), which will in turn be overridden by
archive-services.php (a template file specifically for the archive named "services").
A simple theme looks something like this:
// Theme CSS style.css // Custom functionality for your theme functions.php // Partials to include in subsequent theme files header.php footer.php sidebar.php comments.php // "Archives", (listing views that contain multiple posts) archive.php author.php date.php taxonomy.php tag.php category.php // Individual content pages // Note that home and frontpage templates are not recommended // and they should be replaced by page templates singular.php single.php page.php front-page.php home.php // Misc. Utility Pages index.php (a catch-all if nothing else matches) search.php attachment.php image.php 404.php
<?php get_header(); ?> <?php if ( have_posts() ) while ( have_posts() ) : the_post(); ?> <h1><?php the_title(); ?></h1> <?php the_content(); ?> <?php comments_template( '', true ); ?> <?php endwhile; ?> <?php get_sidebar(); ?> <?php get_footer(); ?>
What's happening here? First, it loads
header.php (similar to a PHP include or require), sets up The Loop, displays
the_content, then includes
footer.php. The Loop does the heavy lifting, setting up a
Post object, which contains all the information for the currently-viewed content.
<?php get_header(); ?> <?php if ( have_posts() ) while ( have_posts() ) : the_post(); ?> <a href="<?php the_permalink(); ?>"<?php the_title(); ?></a> <?php the_excerpt(); ?> <?php endwhile; ?> <?php next_posts_link( 'Older Entries', $the_query->max_num_pages ); previous_posts_link( 'Newer Entries' ); ?> <?php get_sidebar(); ?> <?php get_footer(); ?>
First, it includes
header.php, sets up The Loop, and includes
footer.php. But in this case there are multiple posts in the loop, so instead an excerpt is shown with a link to the individual post.
previous_posts_link are also included so the archive can paginate results.
Out of the box, WordPress supports two types of content:
Pages. Posts are typically used for non-hierarchical content like blog posts. Pages are used for static, standalone content like an About Us page, or a company's Services page with nested sub-pages underneath.
As of version 3.0, developers can define their own custom post types to extend the functionality of WordPress beyond just the basics. In addition to custom post types, you can also create your own custom fields to attach to your posts/pages/custom post types, allowing you to provide a structured way of adding and accessing metadata within your templates. See: Advanced Custom Fields.