The core terms cluster into three groups. Contract anatomy — strike, expiration, premium, intrinsic, extrinsic, ITM, OTM, ATM — describes what an option is. Greeks — delta, gamma, theta, vega, rho — describe how the option's price changes when something else changes. Market mechanics — bid, ask, mid, IV rank, open interest, volume, assignment, exercise — describe how the option behaves when you actually try to trade it.
Master these forty-odd terms and the rest of the curriculum reads like English. Skip them and every subsequent module will feel like translating a foreign language. The Express Lane assumes you have this vocabulary down; the Anchors tier requires it.