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Child Theme - does customization affect the license?

axessJosh asked
I have been using the Twenty-Ten theme to create child themes for my wordpress sites.  I have essentially taken the TwentyTen theme, changed all the things that I generally adjust for a site and made my own template theme essentially.

My question is, am I in violation of any licensing or anything by completely customizing the theme.  I change the theme name on the style.css file and remove the parent theme links so it doesn't get affected by updates.

Can I do a Find and Replace to change all references to Twenty Ten and still be ok with the GPL license?
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Jason C. LevineDon't talk to me.
There's a difference between a Child Theme and copying the new theme over to something completely different.  The former is well-within the GPL.  The latter just has to conform to the following:

- You may freely use the works for any purpose, including commercial ones
- You may freely make derivative works provided that you leave the proper attribution and copyright notices
- You may freely distribute the works and derivative works provided that you make the source code readily available under the same terms

In your case, the second point is the main one.  You should NOT change all references to TwentyTen unless you leave a clear attribution that this theme is a derivative of TwentyTen and their copyright is in force as well as your additional copyrights.


Thanks Jason.

I have not done the find and replace yet because I wasn't sure what it would affect to the site.  I just wanted to be sure I staying in the realm of doing things right, while still using some templates that save some work.  Sounds like as long as I keep info relevant that we started with the Twenty Ten theme, we're staying within the guidelines.

I guess I don't understand where or why a Child Theme should be used.
Don't talk to me.
First, read this:


Basically, a child theme is used when you want to customize a theme but are afraid of an update blowing away your customizations.  The TwentyX themes update with every new version of WordPress, so these are almost always best used by creating a Child Theme so your customizations are preserved.  

The way a child theme works is there is a line the style.css file that references the parent theme and the parent has to be present for the child to work.  There is also a hierarchy of access, where styles, templates and functions get checked in a specific order (child first) and files in the child either replace or at added to the parent.  

So if you copy TwentyTen completely, it will run as a standalone theme.  You are free to change the name to something else and change the files to your heart's content but you are bound to state in the theme source code that this is a derivative of TwentyTen.

A child of TwentyTen requires TwentyTen to be installed on the site and the child references it per the Codex article above.  You are then free to customize it further without any other references necessary because the child reference is the only one you need.

Make sense?