In the GNU Affero General Public License, there is a section that reads:The GNU Affero General Public License is designed specifically to  ensure that, in such cases, the modified source code becomes available  to the community. It requires the operator of a network server to  provide the source code of the modified version running there to the  users of that server. Therefore, public use of a modified version, on  a publicly accessible server, gives the public access to the source  code of the modified version.So clearly I couldn't make a modified version of a piece of software and then put it on the public internet for everyone to access (assuming network software living on a server) without also making the source code available.But what is defined by public here? Do subscription based services where only select paying customers have access count as public?
In the GNU Affero GPL, do paying customers count as the 'public'?
licensing;legal;gnu
The text you quoted is part of the preamble, it is not part of the legally binding terms and conditions.The relevant part is article 13, which states that you have to make the source code available to everybody to whom you make the object code available. Note that this is no different from the normal GPL. The difference between the normal and the Affero versions of the GPL is not to whom you make the source code available, but rather what counts as making the object code available. In the normal GPL, only giving the object code away counts, whereas in the Affero GPL also making it available as a service counts.To repeat: no version of the GPL requires you to make the source code available to the public. In fact, no version of the GPL requires you to make the source code available at all.All versions of the GPL only require you to make the source code available iff you also make the object code available and only to those people to whom you make the object code available.What the Affero GPL adds is the idea that Software-as-a-Service is also a form of making the object code available and thus also requires making the source code available to the users of the service.