royalty free and public domain software If I for example had a picture that was declared public domain and a picture that was declared royalty free, how could/couldn''t I use those two pictures (could I use both in my commercial games for example?) and what''s their difference? a texture claimed freeware couldn''t necessarily be used in commecrial projects, no?

As far as I can tell :

Public domain : You can do whatever you want with it. Everybody (or nobody) owns it.
Royalty free : You don''t have to pay to use it. It is still theirs and may object to the use though.

Your best bet is to ask a lawyer. I don''t think too many people here are lawyers, so they can only give their opinion. A lwyer can give you the facts.

Public domain software is software which was either released into public domain by the author, or it''s copyright ran out. Technicaly no one owns the rights to the product once it''s placed in public domain.

On to royalty free....In order to understand this one you need to know what royalties are.

The easiest way to discribe this is with a music refrence so bear with me:

Lets say Puff Daddy (the rapper) wants to use a sample of the A-Team theme song in his next rap song. Puff Daddy asks permission, and pays the A-Team theme song writer $10 million for the ability to use the sample. However, he tells the A-Team theme song writer that he will recieve royalties on the sale of the album, in addition to the 10 million.

Well anyway lets say it costs puff daddy publisher $50 mill to get this album out the door. In this case no one gets royalties until after the publisher makes it''s $50 million back. Once that happens for every sale Puff Daddy gets a royaltie based on a percentage he negotiated, and so doesn''t the A-Team theme song writer.

Now that you understand what royalties are we can now explain what royalty free means. Basicaly it allows you to not have to pay the author or creator for using their program/code/music on a per sale basis. Most of the time you still have to pay once however, some places will sell graphics cd''s for $200 but they are royalty free. If the thing you wish to use is royalty free and also free then you don''t have to pay anything.