Let’s start with a lead magnet definition:

A lead magnet is used by a company as an incentive for the visitor to hand over their email address. In B2B marketing a lead magnet is often in the form of a downloadable PDF. Other types of lead magnets could be discount codes when a visitor signs up for a newsletter, a webinar or a free tool.

For B2B marketers, getting a visitor’s email address is the first significant step towards building a relationship with a potential customer. 

The goal of a lead magnet is to offer something that the visitor values enough that they are willing to share their personal information with you.