This was true in the past, but today almost all major nations follow the Berne copyright convention (i.e. Europe). After April 1, 1989, everything created in the USA, for example, is copyrighted and protected whether it has a notice or not. The default you must assume for other people's works is that they are copyrighted and may not be copied unless you *know* otherwise. There are some old works that lost protection without notice, but frankly you should not risk it unless you know for sure.
It is true that a notice strengthens the protection, by warning people, and by allowing one to get more and different damages, but it is not necessary. If it looks copyrighted, you must assume it is.
False. Whether you charge can affect the damages awarded in court, but that's the only difference. It's still a violation if you give it away -- and there can still be heavy damages if you hurt the commercial value of the property.
False. Nothing is in the public domain anymore unless the owner explicitly puts it in the public domain(*). Explicitly, as in you have a note from the author/owner saying, "I grant this to the public domain." Those exact words or words very much like them.
Some argue that posting to USENET implicitly grants permission to everybody to copy the posting as much as they like. This is very probably wrong. First, the whole purpose of copyright is to provide protection to people *after* they freely distribute it. For example, George Lucas still owns Star Wars after broadcasting it on free TV or giving copies to lots of people. Secondly, that argument breaks down when one considers what it would mean for you to post an MPEG of Star Wars to the net (other than some really annoyed people with v.32bis modem feeds.) All the copying would still go on, but clearly without permission since you -- unless you are George Lucas -- didn't have the right to give permission to copy in the first place.
(*) It's also in the public domain if the creator has been dead for 50 years. If anybody dead for 50 years is posting to the net, let me know.
See the notes on fair use for a detailed answer, but bear the following in mind:
The "fair use" exemption to copyright law was created to allow commentary, news reporting and education *on* copyrighted works without the permission of the author. In this case, the "on" is important. You must be commenting on or reporting about the *work*, not the subject matter of the work. If you could have reported the facts in your own words, but didn't to save typing, it's probably not fair use. If you needed to demonstrate something about the actual work or writing, then it might be fair use.
Fair use is almost always a short excerpt and almost always attributed. It should not ruin the commercial value of the work (which is why reproduction of the entire work is generally verboten.)
False. Copyright is *never* lost now, unless explicitly given away. You may be thinking of trade marks, which can be weakened or lost if not defended.
You can't copyright a name, or anything short like that. Titles usually don't qualify, but I doubt you could write a song entitled "Everybody's got something to hide except for me and my monkey."
However, you can trademark an adjective, when applied to a generic type of product or service. Like an "Apple" computer. Apple Computer owns that word applied to computers, even though it is also an ordinary word. Apple records owns it when applied to music. Neither owns the word on its own, only in context.
You can't use somebody else's trademark in a way that would unfairly hurt the value of the mark, or in a way that might make people confuse you with the real owner of the mark, or which might allow you to profit from the mark's good name. For example, if I were giving advice on music videos, I would be very wary of trying to label my works with a name like "mtv." :-)
Copyright law is mostly civil law. If you violate copyright you would usually get sued, not charged with a crime. "Innocent until proven guilty" is a principle of criminal law, as is "proof beyond a reasonable doubt." Sorry, but in copyright suits, these don't apply. It's mostly which side the judge or jury believes more.
Actually, recently in the USA commercial copyright violations involving more than 10 copies and/or value over $2500 was made a felony. So watch out. (At least you get the protections of criminal law.)
It's up to the owner to decide if they want the free ads or not. If they want them, they will be sure to contact you. Don't rationalize whether it hurts the owner or not, *ask* them. Usually that's not too hard to do. Time past, ClariNet published the very funny Dave Barry column to a large and appreciative USENET audience for a fee, but some jerk didn't ask, and forwarded it to a mailing list, got caught, and the newspaper chain that employs Dave Barry pulled the column from the net, pissing off everybody who enjoyed it. Even if you can't think of how the author or owner gets hurt, think about the fact that piracy on the net hurts everybody who wants a chance to use this wonderful new technology to do more than read other people's flamewars.
To have a copy is not to have the copyright. All the E-mail you write is copyrighted. However, E-mail is not, unless previously agreed, secret. So you can certainly *report* on what E-mail you are sent, and reveal what it says. You can even quote parts of it to demonstrate. Frankly, somebody who sues over an ordinary message might well lose, because the message has no commercial value, but if you want to stay strictly in the law, you should ask first.
Permission is granted to freely copy thisIf you had not seen a notice like this on the document, you would have to assume you did not have permission to copy it. This document is still protected by you know what even though it has no copyright notice.
document in electronic form, or to print for