The GPL does not require you to release your modified version. You are free to make modifications and use them privately, without ever releasing them.
[Snip] But if you release the modified version to the public in some way, the GPL requires you to make the modified source code available to the program's users, under the GPL.
[^] # Re: Un petit peu embetant, non ?
Posté par theocrite . En réponse à la dépêche Le marché des logiciels libres est arrivé à pleine maturité. Évalué à 3.
The GPL does not require you to release your modified version. You are free to make modifications and use them privately, without ever releasing them.
[Snip]
But if you release the modified version to the public in some way, the GPL requires you to make the modified source code available to the program's users, under the GPL.