SEO is the practice of improving a website so it ranks higher in search engine results, bringing in free ('organic') traffic. On-page SEO covers what you control directly on your site: using target keywords in titles and headings, writing clear meta descriptions, using descriptive URLs, and ensuring fast page load times and mobile-friendliness. Off-page SEO covers external signals, mainly backlinks -- other reputable sites linking to yours -- which search engines treat as a vote of trust. Keyword research, using free tools like Google Keyword Planner or Google Trends, helps you find the actual terms your audience searches for so you create content that matches real demand rather than guesswork.