The Short Answer
Yes, quotes are protected under copyright law.
The Long Answer
As you would expect a lot of quotations are not copyrighted and in fact, some may pose impossible to find out if one is or not, especially if the quotation is from someone whom died many years ago, e.g Winston Churchill.
Most quotations that appear in publications such as books, tv or newspapers will be copyrighted automatically, by the publisher or artist. Whether or not they seek to request take down of the used quote is also another factor, most won't, there's bigger fish to fry and policing everything on the internet costs more money than they would gain from legal action.
To add more complexity you can also not copy quotes found on other websites, because they will often have their own copyright notice that prevents you copying content even through they are not the original owner. For example:
Despite being the largest (and nearly the oldest) quotation website on
the Internet, we haven't yet become so megalomaniacal as to declare we
own the exclusive rights to quotes that other people have said.
However, we do own the copyright to the arrangement of information on
Plus, we can make you agree to stuff through this contract that
further limits your rights, such as by writing this: You agree not to
copy, distribute, display, disseminate, or otherwise reproduce any of
the information on our Site, or our Site itself, without our prior
written permission. This includes, but is not limited to, all original
content (such as BUT NOT LIMITED TO! articles, photographs,
biographies) and a prohibition on collecting aggregated information
from our Site that is in the public domain and publishing it
elsewhere. This prohibition does not extend to uses which would, if
governed solely by the copyright law of the United States, be
considered a "fair use."
Most websites that operate in a grey area of copyright infringements will mostly use a 'user submitted' system and will have a way of users reporting infringement, generally this is enough to keep lawyers at bay, however it doesn't mean your not infringing, just look at the case of
Megavideos, they allowed user submitted content and even actioned DCMA takedowns, but still ended up on the wrong side of the law. Bottomline, its a grey area.
What else can be copyrighted online?
- Software (Games, Applications, Plugins)
- Images (photography, cgi etc)
- Video (Movies, Demos, Clips, TV and even Trailers)
- Sound (Music, Stories, SFX etc)
- Words (Quotes, Text, Lyrics, Trademarks)
- Websites (style design)