Search Engine Optimization

SEO's lose sleep SEOs don't build websites; they build web presence.  SEOs don't design websites; they make your website more usable.  SEOs don't socialize your content; they communicate your value.  SEOs don't spam keywords in content to rank; they integrate keywords into content to sell. SEOs don't sell your products/services; they help you attract buyers for you to sell to.  SEOs don't drive traffic; they drive customers.  SEOs don't create conversions; they make your website more conversion friendly.  SEOs don't write your business plan; they help fulfill it.  SEOs don't manipulate Google's results; they make Google's results relevant. Change from Time to Time - Google updates its algorithm frequently, causing ranking shifts that are known to make digital marketers lose sleep.

In contrast, organic marketing takes time but once it starts yielding results - you will keep getting customers on your website with zero spend on additional marketing. ROI is difficult to predict in advance. Source -  https://yourstory.com/2016/10/content-marketing-tips-startups/