A proposal is the written offer you send a prospect that lays out the solution, the scope, the price, and the terms, and asks for the decision. It usually comes near the end of the sales cycle, after discovery and a demo, and it is the artifact the economic buyer uses to actually say yes. Sending a proposal is not the finish line — it is the start of negotiation and the final follow-up push.
In plain English
A proposal is the formal "here's what we'll do and what it costs" document. It turns the conversation into a concrete decision. Done well, it reflects everything the buyer said they wanted; done badly, it is a generic price sheet that discounting can't save.
Why it matters to you
How you send a proposal shapes whether it becomes closed-won or sits in your pipeline as a maybe. A strong proposal recaps the buyer's priorities, names your champion, and states a clear next step. In an interview, describing a proposal you owned shows you understand the whole arc from opportunity to signature — not just the talk track.
For writing and driving a proposal that gets approved, see Write a Sales Proposal and what to do after you send it.