Wikipedia:Tip of the day/June 3, 2007

Tag your image uploads

When uploading images or other media for use in Wikipedia articles, always remember to add the appropriate copyright tag to show what license the material is under, or if it is in the public domain. You can do this with the drop-down menu that lists common licenses, or leave the list on the default setting and adding the template manually in the box above it.

There is also a list of more copyright tags.