Digital marketing is the process of building and maintaining customer relationships through online activities to generate sales. It consists of key components like search engine optimization (SEO), pay per click (PPC) advertising, social media marketing (SMM), and content marketing. SEO involves optimizing website content and links to achieve natural or organic rankings in search engines. PPC allows targeting visitors within hours but requires ongoing payments. SMM provides targeted traffic at low cost through social media engagement. Measurement tools help track the ROI of digital marketing activities.