This is a very interesting question, and one that is not as easy to answer as it might first seem.   What looks like a single question is in reality four.

1)     Is it possible to copy text from another website onto my own site?
2)     Is it legal for me to use text from another website on my own site?
3)     Is it ethical for me to use text from another website on my own site?
4)     Is it effective to copy text from another site onto my own site?

Is it possible to copy text from another site onto my own site?

The first question is both the easiest to answer, and the least relevant.  Yes, there are any number of ways that you can physically move content from one web site to another, but if it is not legal, ethical, or effective, do you really want to?

Is it legal for me to use text from another website on my own site?

This really depends on how much content you intend to copy, for what purpose, and whether or not you have received the permission of the original author.

The United States’ copyright laws recognize something called Fair Use.  According to Wikipedia, the purpose of Fair Use is to facilitate the study or review of a work under copyright.  Just how far Fair Use extends is an interesting question, and one you would be well served to direct towards a copyright or intellectual property lawyer.

Is it ethical for me to use text from another website on my own site?

If you intend to give full credit to the original author, and will cite them and link to them in a manner they decide, there are no major ethical concerns.

If you intend to claim someone else’s content as your own (which includes quotation without citation), you should make sure that you have the specific permission of the author (and other interested parties) to use their words in this manner.  Ghost writing remains a strong and honorable profession, but if the ghost writer is not a willing party, then what you’re really doing is plagiarizing.

Is it effective to copy text from another website onto my own site?

Because duplicate content was frequently used as a way to fool Google and the other search engines into giving inflated ratings, they have altered their methods to reduce the impact of sites with identical or nearly identical text.  Good content will drive traffic, but if you want to get full credit for that traffic you should include a significant contribution of your own.

What would you suggest if I want to use text from another website on my own?

Ask the author for permission or see if they have posted instructions for those wishing to copy their content.

Assume that the author will want credit for their work.  To do this, you can give them a by-line, a credit box, a bibliographic citation, or even a simple back link.

Honor the original author’s requests.  Many authors will have a preferred format for citation and links back to their site.

If your site consistently uses a particular form of citation, and that happens to differ from the one preferred by the author – be sure to explain what format you use and why.  Give the author an option to opt-out if they are uncomfortable with your chosen method of citation.

I have also now written a blog on using the Creative Commons to locate free online material that you can use on your own website.