Email marketing is the act of sending a commercial message, typically to a group of people, using email. In its broadest sense, every email sent to a potential or current customer could be considered email marketing. It involves using email to send advertisements, request business, or solicit sales or donations.
Email marketing is a form of marketing that can make the customers on your email list aware of new products, discounts, and other services. It can also be a softer sell to educate your audience on the value of your brand or keep them engaged between purchases. It can also be anything in between.