There is no definitive answer to this question, but that has not stopped people trying to answer it. Digital marketing influencer Neil Patel outlines 7 types of online marketing which includes search engine optimisation (SEO), search engine marketing (SEM), social media marketing, pay per click advertising (PPC), affiliate marketing and email marketing. However, as companies and agencies increasingly adopt a more holistic approach to digital marketing, the boundaries surrounding its disciplines become less and less defined.