This guide is a working reference for negotiating, administering, and exiting a commercial lease from the small business side, with the landlord's position set out alongside so both parties can see the trade. It begins with the structural difference between residential and commercial tenancy, then covers space measurement, the four rent structures, operating expense pass-throughs, and percentage rent, each with worked numbers. Extended chapters treat the personal guaranty and its four survivable forms, the tenant improvement allowance and the construction terms that determine who bears delay, and the clause set that decides whether a business survives a downturn. Procedural chapters cover default and remedies, the mitigation question that varies by state, and what a bankruptcy filing does to a lease under the assumption, assignment, and claim-cap provisions. Exit chapters set out assignment, negotiated termination, and defended default, with the timing rule that governs all three. Federal overlays on accessibility, environmental liability, tax treatment, and arbitration are covered. Landlord-side chapters address form drafting and workouts. All authorities are linked to their text on uplaw.us.