Plagiarism involves presenting another person's ideas or words as one's own without proper citation or credit. It includes directly copying text without quotation marks or attribution, paraphrasing another's idea without citation, and submitting another's work as one's own. To avoid plagiarism, students should use direct quotations sparingly and cite sources, paraphrase ideas while introducing and citing the original source, and ensure all work submitted is their own original thoughts and writing. Taking thorough notes, including citations, while researching can help properly incorporate others' work later.