You can use a few different types of free licenses on Commons.
- CC BY-SA: This means it's an "Attribution-ShareAlike" license.
- CC BY: This means you want to get credit for work, including remixes and modifications, but you don't care if the new work is shared under the same license.
- CC ZERO: This means you release your work with no restrictions whatsoever. They can modify, reuse, and sell the work without giving you credit or following a similar license.
It's important to remember that there are no restrictions on others using your work for any purpose. Be clear that when you share your work on Commons, you can't specify it as noncommercial. That helps this information become as widely used as possible by encouraging artists, publishers, and others to use these resources in works that they might sell. However, by including the CC BY-SA attribution, you will ensure that anyone shares your work with the same terms, which will reduce commercial exploitation of your work.