When you upload an image you are asked to provide a license.












What you choose depends on the licence that your image has.


If you are using an image of your own choose the licence you want.  I favour Attribution. if someone wants to use my image that's cool. Just acknowledge me. 

If you have used an image that has a CC license then you must add that licence. It's not necessary to add the image but you should acknowledge it, name the licence and add the website. 

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