Copyright is not an absolute. Potato chips are absolute.
If this is my potato chip, then it's not yours. You can't touch it, eat it or use it for any reason whatsoever, not without asking first. Copyright doesn't work that way.
There is a yin to the yang of copyright protection, and it's called Fair Use. Fair use permits scholars to do their thing, permits those that would do parody or commentary or comparison to be heard. I'm not talking about taking someone's work to make it into a poster or some sort of endorsement--I'm talking about the need for us to be able to comment on each other's work.
Without fair use, it would be impossible to write a negative book review, or compare Shakespeare to the Simpsons. Without fair use, it becomes just about impossible to have a thoughtful discussion about anything that's been published since you were born.
Most web users should know a few simple guidelines, principles so simple that you can generally assume them to be rules. (Worth noting that whether you are in the right or not, a lawyer on retainer can still hassle you--not fair but true):
- You don't need to ask someone's permission to include a link to their site.
- You don't need to ask permission to include a screen shot of a website in a directory, comment on that site or parody it.
- You can quote hundreds of words from a book (for an article or book or on your website) without worrying about it and you certainly don't need a signed release from the original author or publisher. Poems and songs are special exceptions. Then you can worry.
There's a difference between being polite and observing the law. If you quote something (an idea, a notion, a recipe), the right thing to do is give credit.
Photos are a real issue, unless you are clearly commenting on the photo (as opposed to using the photo to make a point that a different photo could make as easily). When in doubt, be the person who took the picture. (Aside: Compfight has an easy to use setting--do a search and hit "commercial" in the left hand column and voila--CC licensed photos, ready to go.)
PS as soon as you make something and fix it in a tangible form, you own the copyright in it. No requirement that you register it with anyone. Putting a © notice is certainly a helpful way to let people know you consider it yours, but the law makes it clear that merely writing your creation down confers copyright to you. And... "all rights reserved" doesn't mean anything any more, just fyi.
PPS Here's what happens when the lawyers go (way) too far.