A more thorough explanation:

An invitation to negotiate is a request for one or more offers, usually as a first step towards creating a contract. It is also known as an invitation seeking offers, invitation to bid, invitation to treat, solicitation for bids, preliminary letter, or offer to chaffer.

1. A company sends out a request for proposals (RFP) to several vendors, asking them to submit their proposals for a new project. This is an invitation to negotiate.

2. A real estate agent puts up a sign outside a property that says "For Sale." This is not an offer, but an invitation to negotiate. A potential buyer can make an offer, but the seller is not obligated to accept it.

3. A government agency issues a request for bids for a construction project. Contractors can submit their bids, but the agency is not obligated to accept any of them. This is an invitation to negotiate.

These examples illustrate how an invitation to negotiate is a preliminary step towards forming a contract. It allows parties to explore their options and negotiate the terms of the contract before making a final agreement.