Are wordpress themes built from scratch

Are wordpress themes usually made from scratch or by building/editing from a theme that is already made. So for example can someone buy a theme from Themeforest, add their own visuals and functionality and sell it as there own? I see a lot of themes that seem to be based off of the same design/concept and was wondering if that was how it is done.

Both.

Themes can be(and should be) and are quite often built from scratch.

People can purchase a theme and edit it how they want it and use it. However, whether they’re allowed to do this or not is a different question. Themes on themeforest often if not always have a license applied to them and therefore you shouldn’t create your themes this way. You can view the license details here. These are rules of course and can’t really stop you from editing them. Just don’t get caught! (I don’t necessarily condone this kind of activity!)

Like bo5ton said, it varies by themes.

However, most of them are under a license which prohibits (either explicitly or implicitly) creating derived works and selling them. It’s usually okay for your own personal use though, as long as the license allows it. (It falls under the same copyright laws as any other “derived” work for anything else covered by copyrights). I highly recommend that if you want to build them to sell them, you should build them from scratch. You can pretty easily build your own “vanilla” base template which you use and then extend that one for each of your new ones. In fact, just swapping the style sheets you could get an infinite number of very nice looking themes.

According to this, any theme for Wordpress is technically under the GPL license: http://wordpress.org/about/license/, however, like they say, it’s a gray area. If you are going to derive from any of them, I highly recommend deriving it from one of the default themes (Twenty Eleven and Twenty Ten), since they have an explicit GPL license.

Hi
a lot of people for as i know makes some new theme simply making a " child theme " from a stable theme, like Genesis. If the “father” theme is released under a GPL License, you can release ( not sell ) your theme as a new product.

J shannon,

I have done many sites from themeforest and then add or take out what i need. I go by the rule do not reinvent the wheel. I have also taken things from one wordpress theme and move them into one i like.