WordPress Getting started with WordPress WordPress Themes


Example

Mapping URLs to specific templates

To fully grasp WordPress themes, you must understand two primary concepts:

  1. Permalinks
  2. The Template Hierarchy

A permalink is a permanent, non-changing URL (or link, to a specific resource. For instance:

  • example.com/about-us/ (a Page in WP)
  • example.com/services/ (a listing of multiple items, also called an "archive" in WP lingo)
  • example.com/services/we-can-do-that-for-you/ (an individual item)

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.

For example: 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").

Here is a great visual reference for the Template Hierarchy

Basic Theme Directory Structure

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

Example of a "Single" (template for an individual post)

<?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_title and the_content, then includes comments.php, sidebar.php, and footer.php. The Loop does the heavy lifting, setting up a Post object, which contains all the information for the currently-viewed content.

Example of an "Archive" (template for a list of multiple posts)

<?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 sidebar.php, and 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. next_posts_link and previous_posts_link are also included so the archive can paginate results.

Posts, Pages, Custom Post Types, and Custom Fields

Out of the box, WordPress supports two types of content: Posts and 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.