Plagiarism is the MOST serious offense in academe. When you borrow ideas, concepts, words, sentences, paragraphs, entire sections or papers, bibliographic sources without attribution this is considered to be plagiarism. If you discuss these items and reference/cite/quote them this is considered to be scholarship. When you do the same without attribution, this is plagiarism.
The standard punishment is F with notation on your student records/transcripts.
If you wish to correct a wrong you have already committed, come see me. I WILL BE CHECKING AND RECHECKING ALREADY GRADED ESSAYS.
At the college level, you are expelled.