Search engine optimization (SEO) involves optimizing websites and webpages to increase traffic from search engines through organic or unpaid search results. Ethical SEO follows search engine guidelines to naturally and manually optimize content, keywords, and links to maintain high quality search results over the long run. Unethical SEO, also called black hat techniques, uses spammy or manipulative methods like hidden text, keyword stuffing, and link farms that are disliked by search engines and can lead to penalties.