Attachment term is used for files uploaded to the WordPress website from the post edit screen. When a media file is uploaded into a post or page, it is considered as an attachment of that post or page. Also, if the webpage is allowing users to download media into their device from the website then also it is known as an attachment.

Attachment is the only file that is connected to a post or page. Not all the files uploaded form media tab is considered as an attachment.

A Media file that is referenced to a specific post is considered as an attachment. If a post is deleted then the media file may become unattached media. It can be reattached to a newer post and also it is possible to attach a single media file to multiple posts.

Theme developers can use attachment features using template tags to change the appearance of the post. examples are the using of Post Images; these images can be set to a default, a category image, or a new image for each post.