We can criticize, comment, report, build upon and teach using ideas of others, but we need to ensure that we are crediting the author or creator properly. This way, when other people go to use our intellectual work they can credit us as well and trace back to the intellectual works and ideas we found interesting and helpful.
According to the Council of Writing Program Administrators, an understanding as a user of information entails:
Plagiarism includes
Here is an example of plagiarism where material written by Mustapha Marrouchi in 2003 is compared to text written twenty-one years earlier by Salman Rushdie. Marrouchi copies Rushdie's orignial text nearly word for word and does not reference the original. Not all plagiarism is this blatant, however. Merely paraphrasing an idea without attribution is still considered to be plagiarism.