Lead capture
Lead capture is the act of collecting a way to contact someone who has shown interest — usually an email address or a phone number — in exchange for something they want.
The exchange is the part that gets skipped. A form that asks for details without offering anything in return is not lead capture; it is a toll booth. What is offered can be small — a booking slot, a quote, an answer — but there has to be something.
How many fields to ask for is the recurring trade-off. Every field costs completions, and every field you skip costs qualification later. The honest rule is to ask only for what changes what you do next: if an answer would not alter your reply, it does not belong on the form.
A captured lead that is never contacted is not a lead, which is why lead capture and a CRM are the same subject rather than two.