Digital marketing is the marketing of products or services using digital technologies on the internet and mobile devices. It includes methods like search engine optimization, social media marketing, content marketing, and email marketing. The major components are internet marketing through websites, search, smartphones, and social media, as well as non-internet channels like television and radio. Digital marketing offers advantages like global reach, measurability, two-way communication, and low cost, but also risks like real-time complaints, negative reputation, and lack of expertise.