Copyright only protects the exact expression of your web pages. It does not protect the facts or ideas you use. If someone copies your ideas, but expresses them in a different way, they are not breaking copyright law. If a piece of work is created independently, but by coincidence happens to be similar to or the same as another previously created piece of work, it is not seen to be breaking copyright law. This can be difficult to prove for the author accused of copyright infringement, but equally difficult to disprove for the copyright owner. Two concepts that make content exempt from copyright law are ‘fair use’ and ‘implied permission’. It is useful to be aware of these exemptions.
The concept of ‘fair use’ is a rather unclear limit to copyright protection. If you use another person’s work, but acknowledge that it is their work, this is allowed under ‘fair use’. If you use another person’s work but do not make any commercial gain from it you may not be breaking copyright law under ‘fair use’. Also, if your use of their work does not negatively impact their income, this may be covered by ‘fair use’.
This is a particularly relevant concept for membership site owners. When one of your members posts a thread on your forum, or a comment on your blog, they are the author of the work, but they are giving you ‘implied permission’ to use it as you wish. This also applies to any e-mail that your customers send to you. Unless they specify otherwise, their words are not protected by copyright law.