Search engine optimization is known for organic or non-paid. There are so many factors (On-Page and Off-Page) to list on googles’ organic search results....
Search Engine Optimization is a practice to appear in search engines without spending any cost. And SEO is also an investment because it takes time to rank in search engines,
Pay per Click is a paid advertising model which used for quick results. These results are shown on the top of the organic search result on Google. And you have to pay for every single click called CPC (Cost per Click).