This excerpt below is from Cañada College's Academic Integrity Policy and the Student Conduct Code.
Academic Integrity (Cheating and Plagiarism)
As members of the college community, students at Cañada are expected to demonstrate integrity in all academic endeavors.
Any act which gains or is intended to gain an unfair academic advantage or which compromises the integrity of the academic standards of the college may be considered an act of academic dishonesty.
Cheating and Plagiarism are violations of the Academic Integrity Policy and the Student Conduct Code and will result in appropriate disciplinary action.
More common than outright plagiarism, students "patch together" thoughts in a recognizable form of writing known as "patchwriting." Instead of synthesizing one's own thoughts and writing original sentences, pieces and phrases of others' work may be pieced together. Read more in this Poynter Institute article.
Whether students mean to plagiarize or not, the consequences of an author's words or phrasing appearing in your work can mean a failing grade on your paper, a failing grade in a class or expulsion from college.
To avoid any of these, keep careful track of where you find your sources and quotes. Use index cards or a Google doc - it doesn't matter how you keep words and ideas next to the author's name, the title of the work and page numbers.
"Administrators said that on final-exam questions, some students supplied identical answers, down to, in some cases, typographical errors, indicating that they had written them together or plagiarized them."
- Perez-Peña, Richard. “Students Disciplined in Harvard Scandal.” New York Times, 1 Feb. 2013.
From Harvard to high school, students have been caught cheating. The news articles below describe how they were caught and what the consequences were.
From Merriam-Webster's online dictionary, a definition: