What does this mean?
Except in those articles where the contrary is explicitly stated, we have a very liberal policy of sharing the intellectual property on our site. One right we do reserve is the right of “attribution.” If you use our materials, you should credit our site with a link, or, if the material is being used in print, with a reference to the source of the material (“source: www.trusaint.com” would do nicely).
Another right we reserve is that your derived product (if you alter materials from our site) not only make attribution, but must also be licensed under a similar agreement. You may not use our material, alter it, and forbid others to use it. This is called “share alike.”
This license allows Wikipedia editors to use our material, since Wikipedia’s intellectual property policies are consistent with it.