The four main types of digital marketing are:SEO, SEM, SMM, Content MarketingSEO, SEM, MMS, WebsiteSEO, Website, Blogs, Digital AdvertisingSEO, SMM, Content Marketing, Digital Marketing

The four main types of digital marketing are: SEO (Search Engine Optimization), SEM (Search Engine Marketing), SMM (Social Media Marketing), and Content Marketing.

1. SEO (Search Engine Optimization): This is the process of optimizing your website to get organic, or un-paid, traffic from the search engine results page. It involves making certain changes to your website design and content that make your site more attractive to a search engine.

2. SEM (Search Engine Marketing): This is a form of Internet marketing that involves the promotion of websites by increasing their visibility in search engine results pages primarily through paid advertising.

3. SMM (Social Media Marketing): This is the use of social media platforms to connect with your audience to build your brand, increase sales, and drive website traffic. This involves publishing great content on your social media profiles, listening to and engaging your followers, analyzing your results, and running social media advertisements.

4. Content Marketing: This is a strategic marketing approach focused on creating and distributing valuable, relevant, and consistent content to attract and retain a clearly defined audience — and, ultimately, to drive profitable customer action.

The other options you mentioned like MMS (Multimedia Messaging Service), Website, Blogs, and Digital Advertising are part of these four main types of digital marketing but they are not the main types themselves.