In WordPress, Media refers to images and files you add to pages. This includes visuals such as photos, graphics and videos and files such as PDFs, Word docs etc.
All media files are stored in the Media Library accessible from the WordPress dashboard menu.
Adding Media (images and files)
To add media to a page, place your cursor where you want to insert the media file and click the Add Media button.
You can then select a file from the Media Library or upload new files.
Editing Media Properties
To edit image properties and/or file links, click the image or link and select the Edit icon.
Adding Image Alt Text
All images must include Alternative Text or Alt Text. This allows visually impaired users using screen readers to understand what the images are and how the images relate to the content on the page.
Alternative Text should be a brief description of the image as you would explain it to someone with their eyes closed. Enter the text when uploading the image using the Alt Text field in the Attachment Details panel, or by clicking the image in the page editor and selecting edit.
For a more in-depth look at web accessibility rules and responsibilities, we recommend visiting webaim.org.