Acceptance of Offer

Hello,

Please can you clarify one point regarding contract law?

Once you’ve started acts of acceptance then the offeror cannot revoke their offer. In addition to this the offeree must communicate to the offerer that they have accepted their offer.

Can you explain how the two relate? If you begin acts of acceptance without communicating the acceptance would this contract be invalid by definition? (unless offeror has revoked their right to communication as in Carlill.)

Thanks