Playing in Someone Else's Sandbox
|See also:||Transformative Work, authorial intent, shared universe|
|Click here for related articles on Fanlore.|
Playing in Someone Else's Sandbox (or in "someone else's backyard") is sharing others’ creativity/intellectual property via the creation of fanworks: fanfic, cosplay, vidding, scantalation, RPGs, fanart, fan films, and much more.
This "sandbox" may be a professionally-created canon universe, one owned by TPTB. It may be a universe or characters created by another fan.
This sharing may be an involuntary collaboration, a recognized collaboration, and it may be a completely invited one.
Those involved in this participatory and transformative culture understand that someone else has created the text/world, and that they are but that the creator no longer has the final say over their creation.
Examples of Use
We're all playing in the same sandbox and I'm happy to share my sand. Would love to see what you do with it! 
Fandom is a big happy sandbox and I am totally willing to share my toys! ^_^"
Lucas knows we're playing in his sandbox — he once even had a panel set up to read the zines to ensure that nothing he considered unfavorable got through... 
I think plagarism in fanfic matters, definitely. It's not a monetary issue, because almost everything is being borrowed... I think of it as misbehaving in the sandbox, so to speak. We're all here to play, and even if it "doesn't really matter" in the long run, it makes things less fun, it makes people angry, and it makes the author feel hurt. 
VariationsOne variation is Marion Zimmer Bradley's 1980 statement:
Another is the fan quoted by Lucasfilm in one of 1981's Open Letters to Star Wars Zine Publishers by Maureen Garrett:I regard myself not as the “inventor” of Darkover, but its discoverer. I others wish to play in my fantasy world, who am I to slam its gates and in churlish voice demand that they build their own? If they are capable of it, they will do someday. Meanwhile, if they wish to write of Darkover, they will.... Or, look at it this way. When I was a little kid, I was a great lover of ‘pretend’ games, but after I was nine or ten, I could never get anyone to play them with me. And now I have a lot of fans, and friends, who will come into my magic garden and play the old ‘pretend games’ with me. 
I suppose I have a rather simplistic view of the subject. If George Lucas and his friends come to my house and went out to play in my backyard, I'd expect them to abide by my rules that you don't stamp on the fuchsias, play basketball in the vegetable garden or tear fronds off my eight foot tall Tasmanian tree fern.