There are many different kinds of plagiarism. Some are easy to spot, others are not. As a writer, you must know what contitutes as plagiarism and what does not. Ignorance does not excuse you from the consequences.
The University of Pittsburgh's undergraduate plagiarism policy (University of Pittsburgh, 2008) lists examples of plagiarism:
Copying text "as is" without quotation marks and with no citation or source.
Reordering the elements of the source text without citation.
Copying pieces (sentences, key phrases) of the source text without citation.
Paraphrasing without citation.
Reproducing information that is not common knowledge or self-evident without citation.
Incorporating an idea heard in conversation without citation.
Using your own past material or another student's material as a new idea without citation.
Paying for another to contribute to your work without citation.
Using software or online translators to translate material without citation.
Paying someone else to do your work, purchasing material, or translating from someone else's material (web-based or hard copy). (Calvano, 2011, p.1)
According to WriteCheck.com
The best defense against plagiarism is knowledge and the practice of effective writing skills. Learning how to paraphrase, quote, and to properly cite and reference material is critical. A writer will never gain good writing skills if he or she does not create their own work. Not procrastinating and beginning papers early will help to squelch the temptation to cheat by plagiarizing. The writer's academic, professional, and personal reputation is too valuable to lose over a moment of laziness or weakness. Using a plagiarism checker is a helpful way to check for plagiarism, even accidental, and ensure that writing is original and well cited. (http://en.writecheck.com/types-of-plagiarism)
References
Calvano, B. (2011). Plagiarism in higher education. Retrieved from http://www.examiner.com/adult-education-in-pittsburgh/plagiarism-higher-education
University of Pittsburgh. (2008). Undergraduate plagiarism policy. Retrieved from http://www.frenchanditalian.pitt.edu/undergrad/about/plagiarism.php
Finding information isn't difficult anymore, however, avoiding adding the information into your work without falling into the plagiarism trap is more difficult. There are 6 easy ways to avoid plagiarism; Paraphrasing, Cite, Quoting, Citing Quotes, Citing your own Material and Referencing. Here are 6 simple steps while writing your work to ensure that your work will be free of plagiarism.
Taken from: http://en.writecheck.com/ways-to-avoid-plagiarism
Expert researchers provide credit to others whose ideas or information they have used. Digital resources often provide a citation that can be copied and pasted. These tools can help with creating your citations.