According to Merriam-Webster Online, the definition of plagiarism is: "to steal and pass off (the words and ideas of another) as one's own."
This is the most concise definition of the word. We added our own emphasis to the word 'ideas' because part of our mission in Ellison Library is to ensure that all STA students understand the depth and scope of what constitutes plagiarism. Ideas can also indeed be plagiarized. In the United States things such as ideas, inventions and original research are considered intellectual property and are safeguarded as such by laws and statutes.
Other fundamental keys to understanding what constitutes an act of plagiarism, according to Plagiarism.org:
A simple mantra to keep in mind: WHEN IN DOUBT ALWAYS CITE
Yes, the fundamentals of tenets of what constitutes an act of plagiarism most definitely apply to digital media such as photographs, images, video and other forms of audio-visual content. Once again, according to Plagiarism.org, "Using an image, video or piece of music in a work you have produced without receiving proper permission or providing appropriate citation is plagiarism."
So by definition the following activities can and will be considered plagiarism:
Turnitin has a excellent visual tutorial called The Plagiarism Spectrum.
Cornell University has put together a useful set of Plagiarism Exercises (open to the general public). These exercises are to be helpful for those still uncertain about the conceptual mechanics of plagiarism.
Similarly, Yale University's Center for Teaching and Learning has also assembled a Plagiarism Quiz open to the general public.
Get certified! Indiana University has created a series of age and education-level appropriate Certification Tests. Test your knowledge and earn a certificate!
Goucher College has designed a quiz called 'Plagiarism-by-Paraphrase Risk.' This exercise can help you learn the boundaries between paraphrasing and plagiarism. As a bonus, the quiz can be taken by discipline (i.e. Science, Economics, Literature etc)
Understanding and Preventing Plagiarism
This is a great resource that covers the basics of what constitutes plagiarism, including excellent examples of how to summarize, paraphrase and beyond.