In the early days of home computers software was truly sold, much the same way as a book is sold. You owned the copy you had bought and were free to use it, abuse it, or even reverse-engineer and hack it as much as you liked. But the author still had CopyRight on it. So although you owned the software you still weren't allowed to make copies for redistribution without the author's permission. In the days before SoftwareLicensing and the DMCA, breaking the copy protection on your own purchased games was completely legal as long as you didn't make copies afterwards!
In order to keep better control over who was using their software, some companies (AT&T, DEC?) started to lease their software rather than selling it outright. You would pay for the use of an OperatingSystem or Application a year at a time. And although it was installed on your computer you didn't own it, you only had a licence to use it. Uusally these licences would also specify how many users could log in, or how many CPU's the OS could utilise.
Nowdays when you 'purchase' commercial software you generally don't buy it at all (as in transfer of ownership); you license it. Since you don't own the software the licensee can impose restrictions on how you're allowed to use the software, when or if you're allowed to resell it, and so on.
License is a verb; licence is a noun. However, Americans care not for this kind of distinction, so the text of all the licences you will read use the spelling "license", and as such that's what you'll find on our wiki.
The GNU project turned licensing upside down by introducing CopyLeft; a license with different restrictions: the software was still CopyRight (it wasn't released to the PublicDomain), but with terms saying that if you gave someone a copy of the program you also had to give them the SourceCode for the program if they asked for it; and under the same license. That way you cannot take software released under a license like the GPL and take away the freedoms it affords you.
As Pamela Jones of Groklaw explains, a licence is legal permission to do something you wouldn't otherwise be allowed to do. The GPL is a CopyRight licence; it grants you permission from the copyright holder to make and distribute copies of the program.
The GPL is not an End User Licence; "Activities other than copying, distribution and modification are not covered by this License; they are outside its scope." and further "You are not required to accept this License, since you have not signed it. However, nothing else grants you permission to modify or distribute the Program or its derivative works. These actions are prohibited by law if you do not accept this License."
Since several people in WLUG were/are apparently unsatisfied with my interpretation, I sent an email to the FreeSoftwareFoundation asking for clarification;
That's not accurate. You own a copy of GPL code just like you own a copy of a book.
Thank you Dave.
Software can also be DualLicensed, commonly released free under the GPL, and commercially under a second license.