different software licenses - what do they mean (yes, really)
 

Ok, I've never read a software license in my life. You got me. I actually deserve it for once so please flame me at will- but after you are done please give me a bit of understanding on this.

I usually just ask if something is free or not. If something is open source can I change it and start giving away the modified version? Can I sell this modified version? Can I sell it like it was before when I did nothing but slap my name on it?

That last question is just for understanding, I don't really intend to do that. However, I would like to combine a few bits of open source, add a small enhancement or two, and sell it. I'm guessing this is either ok, or there are different kinds of open source licenses and it is ok for some of them.

Depending on the original license whether or not you can sell it, I know GPL you have to provide the source code that you modified so it's worthless to sell even if it was allowed

As any license It's always:

1) USE
2) TERRITORY
3) License term

As for software and most probably being an end consumer, you can pretty much mark off the territory, the license term will not be limited unless it's a free trial and the use is the very key thing as well as make sure to check if the updates / new versions etc. are included in the license fee.