SEO refers to Search Engine Optimization. When you type any question in google then enter search button you get a list of web results. Users normally visit top list of website. It's because of powerful web marketing that's called Search Engine Optimization.
SEO helps you rank your website higher than millions or billions of other sites in response to a query. It is an internet marketing strategy.
Directory and search engine submission
Appropriate web site linking from other sites
Meta tag and html design
Well written website content
Well-structured web page design
Meta tag optimization
Try for top ten rankings
Search engine submission
Keywords based optimization strategy
Make your landing pages search engine friendly
Make your secondary pages search engine friendly
Try for indented listing