Twelve lock types - pin tumbler, wafer, disc-detainer, lever, tubular, magnetic, electronic, combination, padlock, deadbolt, smart, bicycle U-lock. For each: how the mechanism works in principle, and the known weakness in its design. Fifteen technical terms (plug, shear line, bitting, bumping, spool driver pin, false set). A How section walks through pin-tumbler operation in plain English. Educational. Locksport is legal in many places; picking what you do not own is not.