pla·gia·rism
"taking someone else's work, idea, etc., and passing it off as one's own"
Any time you quote or paraphrase what someone else has written you must provide a proper citation for the source in your list of references or bibliography.
Type 1: Copy and Paste Plagiarism or Direct Plagiarism
When you copy a sentence, phrase, or paragraph word for word, but do not quote your source.
Type 2: Word Switch Plagiarism
When you rephrase a person's work and insert it into your own work without acknowledging its original source. If you take a sentence from a source and change a few words without acknowledging your source, it is still plagiarism.
This is not paraphrasing. For information on how to correctly paraphrase, see When To Cite.
Type 3: Mosaic or Blending Plagiarism
When you: mix words or ideas from an unacknowledged source in with your own words or ideas; mix together uncited words and ideas from several sources into a single work; or mix together properly cited uses of a source with uncited uses.
Type 4: Insufficient Acknowledgement
When you correctly cite your source once, but continue to use the author's work with out giving additional proper citation.
Type 5: Self-Plagiarism
When you use a paper or assignment completed for one class to satisfy the assignment for a different class. Even if you modify a previous paper or assignment, you must get permission from your professor/ instructor and correctly cite your previous paper.
Source: University of South Alabama