A lead magnet is a piece of digital content, like a guide, report, or free course, that is used by marketers to grow email lists. Lead magnets provide value to users by solving problems or educating them in exchange for their contact information. They are designed to create a sense of urgency and build trust between the marketer and potential customer. Common characteristics of effective lead magnets include being extremely helpful, seen as a resource rather than an advertisement, and focusing on solving user problems.