Qualquer arquivo carregado no Wikimedia Commons tem de estar sob uma licença de conteúdo livre ou em domínio público, devendo possuir informação o suficiente possível sobre os seus direitos autorais. Em detalhe, além de ter de colocar uma marcação de licença (veja Commons:Copyright tags/pt-br), você deve garantir que outros tenham a informação suficiente para verificar essa licença, providenciando dados sobre o autor e a fonte.
Source
Where did the file come from?
A GNU Free Documentation License e várias licenças Creative Commons requerem que seja feita atribuição. Se você for o criador do arquivo, é recomendável que a atribuição seja formalmente feita a si na descrição. A melhor forma de usar é "Nome verdadeiro ([[User:Nome de usuário|Nome de usuário]])".
If you are uploading a file or image that you have created entirely by yourself, you should mark the source field as |source={{Own}} (this is done for you if you use the upload wizard and select "This file is my own work" during the "Release rights" portion of the process); if you are uploading your own photograph of someone else's work, you should use |source={{Self-photographed}}; if you are uploading your own image that is based on other images already on Commons, you should use the {{Own based}} template like this: |source={{own based |1= |2=}} and after the |1= you should put the name of the first image that you based your own image on (e.g., |1=Myphoto.jpg); if you used a second image as well, place the name of that image after |2=, otherwise you may leave this part of the template blank.
If you are uploading a file that originally came from an external website, you should provide at least a link to the web page (i.e., the URL) on which the image or file is displayed (that is, not the web address of the file itself, but rather the web page containing the file). If that page does not also fully explain the freely licensed copyright status of the file, you should also provide a second link to a related page that discusses the website's content copyright, such as its terms of use. Note that it is entirely possible for different versions of what appear to be the exact same image to have been released under different licenses, so tread carefully.[1]
Para conteúdo que você indique como pertencendo ao domínio público, é importante conhecer a data em que o conteúdo foi criado, de modo a saber se os seus direitos autorais realmente expiraram. É também útil providenciar informação sobre o período de vida do autor. Em casos de obras de arte com vários séculos de existência, este detalhe terá menor importância do que, por exemplo, uma fotografia do século XX.
A licensing template must be included on the file's description page in order to ensure that the file is freely usable and modifiable under our licensing criteria ("by anyone, for any purpose, even commercially"). If the file's description page doesn't contain a licensing template, then we can't be sure if the file meets our criteria; it might in fact be a copyright violation. Furthermore, it's important for potential reusers to know how to properly reuse the file – some licenses, for example, require one to name the copyright holder of the file ("attribution") and to apply the same license to derivative works ("share-alike"). Licensing templates are usually placed below a == {{int:license-header}} == section header and above any [[Category:]] links.
Notas
↑For example, a photographer may release a low-resolution version of a photograph under a public domain license, while retaining full copyright protection to a much higher resolution version of the same image.
