The properties of cylindrical magnetic “bubble” domains have been extensively described in the literature. Our understanding of bubble technology has now progressed to the point where it is possible to undertake the design and evaluation of specific bubble systems. Bubble domains, cylindrical islands of reverse magnetization, exist in specially prepared single crystal uniaxial magnetic platelets and epitaxial films. These domains are manipulated by localized magnetic fields generated by currents applied to conductors (conductor access) or inplane fields applied to structured permalloy patterns (field access). An important application of bubbles will be in bulk storage. Study of propagation circuits indicates that reasonable field access memory design objectives are (1) in-plane field frequency, 0.1–10 MHz; (2) in-plane field, 10–30 Oe; (3) storage density, 1.5–10 megabits/in.2; (4) bits/chip, 10 000–100 000.