Glossary
What is Lead?
inquiry, contact
A lead is someone who showed interest in what you sell (form, call, message) but has not bought yet.
Example
Someone sees an ad, visits your site, and asks for a quote. From that moment they are a lead. If they are called, talk, and eventually buy, they become a customer.
Why it matters
Leads go cold fast: the minutes right after they ask are the most valuable. That is why time to first contact matters, and why the same person should not appear multiple times in your list.
Lead and deal
A lead is the person. A specific possible sale with them is called a deal.