This document summarizes key concepts around proposals (offers) and their legal rules from a lecture on business law and legal environment. It defines a proposal as one person expressing willingness to do or abstain from an act to another with the goal of obtaining the other's assent. A proposal must meet three essentials - express willingness to an act, be expressed to another person, and aim to obtain their assent. It then outlines legal rules for valid offers, including the offer must be certain, not an invitation, and communicated to the offeree. The document concludes by listing ways an offer can lapse, such as after a reasonable time, rejection, death or insanity of parties, revocation, or illegality/