What exactly is plagiarism?

Plagiarism (Use the linked words in the text to find out more)

Plagiarism (from Latin plagiare "to kidnap") is the practice of claiming, or implying, original authorship or incorporating material from someone else's written or creative work, in whole or in part, into one's own without adequate acknowledgement. Unlike cases of forgery, in which the authenticity of the writing, document, or some other kind of object, itself is in question, plagiarism is concerned with the issue of false attribution. Plagiarism can also occur unconsciously; in some cultures certain forms of plagiarism are accepted because the concept can be interpreted differently.
Within academia, plagiarism by students, professors, or researchers is considered academic dishonesty or academic fraud and offenders are subject to academic censure. In journalism, plagiarism is considered a breach of journalistic ethics, and reporters caught plagiarizing typically face disciplinary measures ranging from suspension to termination. Some individuals caught plagiarizing in academic or journalistic contexts claim that they plagiarized unintentionally, by failing to include quotations or give the appropriate citation. While plagiarism in scholarship and journalism has a centuries-old history, the development of the Internet, where articles appear as electronic text, has made the physical act of copying the work of others much easier.
Plagiarism is different from copyright infringement. While both terms may apply to a particular act, they emphasize different aspects of the transgression. Copyright infringement is a violation of the rights of the copyright holder, when material is used without the copyright holder's consent. On the other hand, plagiarism is concerned with the unearned increment to the plagiarizing author's reputation.
wikipedia.com

Plagiarism - how to avoid it

1. Read - write down the main ideas (the ones that are useful to you)

2. Divide the points into:-

a) generally known ideas (eg. Water is vital to all forms of life.)

b) not generally known ideas/information (Water degradation is doubled in areas frequented by tourists.)

c) specific information (More water is used in tourist areas than in other areas - 880 litres per person per day vs 250 litres pppd)

Use without citing (a)

Use only after citing (b), (c)

But

i) If you use (a) from a source, still try to paraphrase it (it it into your own words)

ii) Use the information in an order that is different to the order in the original source (ie. Do not simply copy from someone else's text.)

iii) Don't let the original text dominate your writing - you choose what to write, and in what order you wish to write it.
Robert L. Fielding