An invoice is the bill you send a customer after (or before) the work is done. Build it from scratch, prefill it from a job, or pull in an approved quote — then send it by email with an optional online payment link, track its status from Draft to Paid, and download a PDF copy.
Before you start: sign in with an account that can manage invoices (an operator/employer account), and have a customer to bill — see create a customer.