Wikimedia Commons is basically an international, open-source media repository.
Media of all description (pictures, graphics, video and audio) are posted by the users/members; most works are original in nature and are shared under various license agreements (which the originator of the works selects when posting).
In effect many of the pictures, maps and graphics that you will find embedded in Wikipedia are stored in Wikimedia Commons.
Once registered, users can add, edit or append to existing media files.
Wikimedia Commons was created in 2004.
You can find images of bullfrogs on wikimedia commons.
Wikimedia Commons has files with 11 different types of extensions available for use. Of those 11, they recommend, JPEG, SVG, PNG, or XCF. They do not allow BMP files.
Yes, but they are actually hosted on Wikimedia Commons, a freely licensed media site.
I have put a few links to pictures of medieval cannon in Wikimedia Commons below:
Most are, but many of them carry Creative Commons licenses allowing many free uses. Copyright status is well marked on each file's page.
Yes, wikipedia is a non-profit. Wikipedia is part of The Wikimedia Foundation Inc, which is a non-profit charitable organization, which also includes: Wikipedia, Wiktionary, Wikiquote, Wikibooks, Wikisource, Wikimedia Commons, Wikispecies, Wikinews, Wikiversity, Wikimedia Incubator and Meta-Wiki.
I would suggest Wikimedia Commons. If you follow the link below, you will find a wealth of links to subjects, each of which has links to medieval pictures.
Because Wikipedia is part of the Wikimedia Foundation! Wikimedia owns Wikipedia.
Wikimedia Foundation was created in 2003.
The population of Wikimedia Foundation is 2,011.
The population of Wikimedia Foundation is 75.