Legal Question in Business Law in California

A contract is formed and the parties are bound when an offer is made by one party and the offer is accepted by the other party. This simple rule is modified and explained by a bunch of additional rules that, for example, define what is a valid offer that might lead to an enforceable contract, and define what amounts to a proper acceptance that'll result in a binding contract. So, I'd have to say that an "offer letter" does not in itself form a binding contract, BUT if it is accepted by the offeree, then maybe the parties are bound. There is a long list of additional factors that might prevent formation of a valid contract, including whether the parties are competent, whether the necessary terms are present, whether the subject matter is legal, etc. etc.