I've had a search and there were a few threads about this, but they couldn't quite answer my questions.

As I understand it: I can write my own software and sell it under the GPL license. I can charge any amount I want (from nothing to £10,000,00 (or more) if I want). When someone buys it they may modify it if they want. Whether they do or not they then may sell it on for any amount they wish (or give it away).

Hopefully I got that correct. My questions are:
Can I (should I) include the phase "Copyright (c) 2005 <my name>" within it?
If so can/should the person who bought it off me change it?

nope.

You can charge any amount of money you like for the service of compiling packaging and delivering the software. however you must make the source code freely available for anyone who wants it.

so you could charg for a pre compiled binary, but you would have to let anyone who wanted to to compile it themselves for free.

edit: and yes, even if you sell a pre-compiled binary, the customer could freely download your source code and modify it.

Example.... Fodora could start charging for their ISO's images that are currently free.
however, if they did that, i would sill be allowed to download their source code for free, compile it for free, add it to an ISO for free, then let others download it from me for free.

The GPL licence was set up to try and make software free and availble for public consumption. Hence, GPL is set up in a way that selling it is quite difficult. If you create some software that uses another bit of software that uses GPL then you HAVE to make that software availble for the public. So the question needs to be asked: whats the point of trying to sell it?

If you create the software and dont use the GPL licence (i.e. copyright it yours) then you can sell it for as much as you want.

At least thats how i undertstand it.

OK, I was under the impression that although anyone could modify it it was I still copyrighted it.

I've almost finished making a website which is in PHP and I hope then to made extra money for selling the code so others can set up their own site. I thought I'd charge lots and see how it went. If I see it with a traditional (proprietry) license then people openly flaunt it anyway and sell it on and make profit. And realistically I can't take them to court over it. So I thought I'd try this.

If you head over to the home of the PL, I think they have links to descriptions of other licences. You don't have to use the GPL, you can use any of them. All you have to remember is that you can only sell it for what it's worth - if it does the same as a free tool (speech and beer) ten you won't sell any copies.

What you are selling there is the skill you have of actually using the GPL software i.e. PHP. but you cant then sell the code you have written.

qwijibow, I think you may be wrong. as I understand it I only have to supply source code to someone who has purchased the 'pre-compiled' software. I think if someone e-mailed me and said "I WANT THE SOURCE CODE!" I could rightfully say: "No, you can have it if you buy the software from me".

no, that is definitely not correct. that's exactly what the GPL is not about. the code must be available on request to ANYONE. What you are suggesting is that it is possible to impose a direct link between the purchase of a given article and obtaining the code without it. so implicitly you must "buy" the source code.

Frustin: I think you are also wrong. If I write some software in C++ or if I write it in PHP, PERL, BASIC.. I still am able to sell the software I have created. And I choose whatever license I feel is appropriate and sell it for what ever I feel is appropriate. I think the GPL allows it to be sold in this way.

Yes I realise there are other licenses and I could look into each, but if it takes this much effort in order to understand them all then I am going to get fed-up before I sell the software ;o)

acid_kewpie: I believe I only have to provide the source code to people who buy the software from me:
http://www.gnu.org/licenses/gpl-faq....bilityToPublic

If anyone buys it from me they can then get the source code (if they want) and do whatever they want as long as it stays GPL.

Sorry i didnt mean (although i said it) that if you write a program in PHP that you are automatically under the GPL. I meant that if you use software that is covered under GPL your code that you write is covered under GPL also.

Again i might be wrong.

qwijibow: Your statement is slightly misinformed

Under the GPL: You can sell your software. You only have to give someone access to your sourcecode if they have access to your software. Since you are selling your software, the only way for them to get access to the sourcecode is to buy a copy.

However, if someone were to buy a copy of your software and download the sourcecode, they would be allowed to redistribute the code as long as it fell under the GPL.

http://www.gnu.org/copyleft/gpl.html#SEC3

Please people, read the facts before misinforming the newbies

Yes, that's what I understood. I only have to provide source code to someone who I have distributed the software to. And in the case of PHP files (which my software is) I simply receive payment and send them the scripts.

Now, would I be right in saying that as it is supplyed to them without warranty I don't need to supply instructions. My theory is to give basic instructions and charge an additional amount to install it and get it up and running. I'm not trying to rip people off, I just want to provide an additional service and charge for my time.

I feel that the misunderstanding is preventing more people from giving 'free software' a go.
I think most people assume you have to provide it to people at no cost (or just the cost of your time and the CD etc you distribute it on.

Now Here is another question... If I sell version 1.0 of my software to someone do I have to supply a lifetime of sourcecode updates... ie when I finish making version 1.1, 1.2, 2.0 etc do I have to supply the source (and binaries if applicable) to them. As I understand it I only need to supply the version they have been supplied with. And when the next version is made they'd have to buy that version off me to get the source for that one. What does anyone else think?

If you sell version 1.0 to someone, they have access to 1.0 sourcecode. If you release 1.1, they don't have access to it's source unless they also pay for it. You would be kind of an ass not to provide some sort of an upgrade plan though...