is always protected by copyright - either that of the site owner, or that of the person who originally wrote the text.
If you want to use extracts you must ask for permission, and be warned that it will not always be granted. In the main, people will not mind, provided you comply with certain requirements. Common among these are:-
1. Text must have an attribution - a statement telling people where the text originally came from.
2. The text must not be altered in any way - it must be quoted verbatim.
3. It must not be used out of context - it must be used on a page that is relevant to its subject matter.
4. You may not take one copyright permission to mean a blanket permission - the text must only be used once, unless the copyright owner says otherwise.
5. Do not think that you can make a couple of alterations and 'pass off' the text as your own - because you can't.
Images are subject to similar restrictions, and again you must not take one from a site unless you have a clear consent from the copyright holder (who may be a different person from the site owner).
Play by the rules and you'll be able to hold your head up, infringe someone's copyright and you might find yourself faced with a legal action.