Attachments illustrate pages and add supporting information
A page can also have files attached (called attachments, naturally), which provide more information on the page's topic. Attachments can be any kind of file.
Some attachments contain images (such as PNGs, JPGs, & GIFs) and can be embedded on the page using wiki markup. Other attachments (such as PDFs, Word documents, text files, & spreadsheets) are downloaded or viewed separately. These can be displayed on the page as links, which a user clicks to download.
Attachments can be images or any other kind of file
Images can be displayed directly on a page, and other files can be downloaded via links
Attachments are searchable
As a bonus, most files that contain text are also searchable. So the wiki can help you find text whether it appears in a page or an attachment. Searchable files include text files, Word documents, spreadsheets, PowerPoint presentations, and most PDFs.
Example
Lorem ipsum dolor sit amet, consectetuer adipiscing elit.
Aliquam fermentum vestibulum est. Sed quis tortor.