It's theft.
If someone deliberately takes another's intellectual property and attempts to present it as his own work, that's plagiarism. We all know that. We also know that lifting complete essays or theses or purchasing a "college paper" online and passing it in for credit can get you booted out of school or worse.
We might have read or heard about unwitting parents getting slapped with huge multi-thousand dollar fines because their children had illegally downloaded music files and "shared" them online. Stealing another's creative work in written form is the same thing.
One can be guilty of plagiarism when "quoting" another's work without attribution. That's never okay.
Even if you do identify the original source, if you might be stepping into dangerous ground if you just "quote" it without commenting upon it. There are specific instances in which we can quote someone else's work, but in these cases we have to follow the rules of "fair use." That means we are using just a portion of the original work for a critical review, a scholarly paper, or the like. You can't just quote Bob Dylan's lyrics just because you "feel" like it.
Elsewhere on these forums a member stated that he (or she) believed that not being able to quote another's work infringed on one's "free speech." The countries which hold personal liberties sacred (such as the one in which I proudly reside) allows self-expression with very few limits (such as the famous admonition against a false shout of "fire!" in a crowded theatre.) For the most part, I can say or write anything I damned well please, as long as I am willing to take responsibility for what I say and that the words I use are my own.
Free societies which make a point of civil liberties aren't all one-sided. Other citizens have rights as well, among them the right not to have their intellectual property stolen out from under them.
The aforementioned LitNutter who thought his free speech rights were compromised mentioned that the copyright laws were designed mainly to protect monetary interests, the rationale, I suppose, being that extremely wealthy artists and performers wouldn't miss a few cents in royalty payments here and there. Imagine if every fan thought this way and acted accordingly -- we're talking about a substantial hit. And that's not just to the
victim-- just like the illegal downloaders, the plagiarist himself can be held liable for hundreds, if not thousands, of dollars in fines and damages.
There's an old joke that goes "Whenever anyone says 'It's not the money, it's the principle,' it's really the money." In the case of stealing another's creative work, it is the principle, though.
Let me give you a case in point, one that is close to home.
A little over two years ago there was a crisis on the Literature Network Forum. A person maintaining another website had systematically lifted numerous original poems written by LitNet members and posted them without any form of attribution on his or her own website. One of our members discovered this by chance, when she saw the queue of poems on that site, all allegedly written by screen name "Personal Poetry." The alert LitNutter noticed that these were the same titles --and complete poems--that had originally appeared on the LitNet. Those of us whose poems had been stolen were horrified; one LitNet member said that she felt "violated." Another LitNet member graciously, painstaking, and tirelessly worked to have the stolen works taken down.
So you can see the damage that plagiarism can do when not even one cent changes hands. If someone lifted your work and posted it elsewhere without giving you credit, how would you feel?
Realistically speaking, nobody is going to object if you sing a hit song in the shower or rock along with the car radio. There is a difference between private and public use. When you post something on a website, such as this one, it automatically becomes public, no matter how many users log on. When you register as a member of the Literature Network Forum that means that you agree to follow the rules, such as this one-- which I'm quoting fairly!--
"5. If you are going to refer to or use content from other sites, authors, or entities, you must include a link or citation for it. You cannot copy and paste entire articles, stories, poems, or etc. from other sites or entities as that is copyright infringement, and contributes nothing to discussion. You should not need more than a few lines, sentences, or maybe a paragraph, to make your point in reference to the topic/discussion. From Copyright.gov ; “Under the fair use doctrine of the U.S. copyright statute, it is permissible to use limited portions of a work including quotes, for purposes such as commentary, criticism, news reporting, and scholarly reports.” Passing off others’ work as your own, whether unintentionally or purposefully, is copyright infringement, and the Literature Network abides by the Copyright Laws of the United States of America and of other countries where applicable."
I hope I haven't offended anyone or insulted anyone's intelligence by bringing up this topic, but there are occasions when I think I should try to step up to the plate offering what little I can to do the right thing. In addition to the LitNet anecdote mentioned above, I've lived long enough to have experienced how heartbreaking it was when, after spending time, effort, and hope in the attempt to have my work accepted, it had been taken out from under me. So please read and heed:
Plagiarism is always wrong. It's not only good manners, it's the law.