How WordPress handles media elements

- If you look at the web the way a computer sees it, it's entirely based on text, but for us humans what makes the web so exciting is media. Images, audio, video, and advanced documents. Now that you know how to create, edit, and publish text with WordPress, it's time to look at how we can add media elements into the mix, and that starts with understanding how WordPress handles media elements. When we talk about media elements in WordPress or anywhere else on the web, we can group them into two main categories: Local Content that is uploaded to and lives on the site and Embedded Content that lives somewhere else.

Typically you'll find images and documents in the local content group while audio and video live somewhere else. We'll address embedded content towards the end of this chapter so for now let's focus on local content and, in particular, images. In WordPress, you can upload media elements either directly from the content editor while you're creating new content, or from the media view in the admin panel. When you upload a media element, WordPress creates what's known as an Attachment Post for that element.

This attachment post is similar to your regular posts but it has some crucial differences. An attachment post is created to hold all the data about an attachment. Either an image, document, or another media file. It has a title, an alternative text attribute, a caption, a description, and a link to the media file that was uploaded. Most importantly, it has a relational link or links that tie the attachment to the post or page where it was added.

So, when you upload and add an image to your post, you're actually creating an attachment post for the image and then using the attachment post data to display the image in your post. And once that attachment post has been created, you can add the same image with the same data to other posts as well without having to re-upload anything because each image lives in its own independent attachment post. And there's more. When you upload an image, WordPress doesn't just save that image.

It creates many different versions of that image for you to use. It creates a large image, a medium image, and a square thumbnail in addition to the original. When you add an image to a post or a page, you can choose which of these sizes you want to use and WordPress will provide the correct image file for the size you pick. The image sizes that are created are controlled in part by the current activated theme, in part by WordPress default, and in part by you. Though I wouldn't recommend it, you can go to Settings and then Media and change the default sizes for images uploaded in the future.

In this chapter we'll look at adding images to posts and pages, managing media items, and embedding external content.