1. An academic offense than can result in a lower or even a failing grade, suspension, or--in severe cases--dismissal from the University.
2. Not a breach of law, but a profound breach of ethics.
3. Just plain DUMB, because properly acknowledging the sources upon which your own work is built only improves your grade. There is no downside to doing the right thing, whereas the penalties for plagiarism are severe and long-term.
Understand plagiarism and avoid it: