Email marketing is a direct digital marketing technique where businesses send promotional messages or advertisements to a target audience via email. It involves building an email list of subscribers who have opted-in to receive communications from the business, and then sending out targeted and personalized emails to that list. Email marketing can be used to promote products or services, provide educational content, build brand awareness, or drive website traffic. The success of an email marketing campaign can be measured by open rates, click-through rates, and conversions.