Digital marketing has grown to $100 billion worldwide. It includes display advertising, search marketing, social media marketing, and affiliation marketing. Display advertising uses banners and other ad units to target users based on location, behaviors, and demographics. Search marketing involves search engine optimization to increase organic search traffic and search engine marketing by bidding on keywords. Social media marketing utilizes platforms like Facebook to target users based on interests and connections. Affiliation programs pay publishers and marketers per action like a sale or form submission. Success across all digital marketing channels is measured using various metrics and goals.