Images are a key part of illustration in Wikimedia wikis. Most images are uploaded to the Wikimedia Commons, but some are uploaded to the site itself (mostly CD/DVD/game covers for copyright reasons). The Wikimedia Commons, the main upload centre for images, is meant to be used exclusively for content under a free license, including content in the public domain, content under compatible free licenses, and content you created yourself and consent to release under a free license. To insert a photo from Commons, you have to link it. I am going to use the example of a flower.

[[File:Flower.png|thumb|left|Caption]]

This code produces this result: