Definition:

The process of turning a website visitor into a paying customer or lead

Example:

Let’s say you have an online store that sells shoes. A website visitor comes to your site and browses through your products but doesn’t make a purchase. To convert this visitor into a paying customer, you might offer them a discount code or a free shipping offer if they make a purchase within the next 24 hours. If the visitor takes you up on this offer and makes a purchase, they have been successfully converted into a paying customer.

Alternatively, if the visitor is not ready to make a purchase but is interested in your products, you might offer them a free e-book or a newsletter subscription in exchange for their email address. This would convert the visitor into a lead, which you can then follow up with through email marketing campaigns in the hopes of converting them into a paying customer at a later time.