Sales process
The stages a deal passes through, each a claim about the buyer.
A sales process is not a script for the seller. It is a claim about the buyer: each stage says the buyer has reached this point. If the claim is false, every number built on it is false too. A sales methodology (how to behave in a deal) is different from the process (where the deal really is).
Name stages after something the buyer did, not something the seller did. "Proposal sent" is a seller activity. Once sent, the deal sits there whatever the buyer does, and fills with hope.
Find your way around
Learn it in the course, copy it from a playbook, see it work in a case study.