Unethical practices on the internet include plagiarism, phishing, hacking, spamming, and software piracy. Plagiarism involves presenting someone else's work or ideas as your own without proper attribution. To avoid plagiarism, one must include references and citations. Spamming involves sending unwanted bulk emails for commercial advertising purposes and can be used to spread viruses or conduct phishing attacks. To prevent spamming, users should reject messages from those not in their contact list and avoid clicking links from unknown sources.