  Magnetic skyrmion, a swirling spin texture, in chiral magnets is
characterized by (i) nano-scale size ($\sim$1nm -- 100nm), (ii) topological
stability, and (iii) gyro-dynamics. These features are shown to be advantageous
for (a) high-density data-storage, (b) nonvolatile memory, and (c) ultra-low
current and energy cost manipulation, respectively. By the numerical
simulations of Landau-Lifshitz-Gilbert equation, the elementary functions of
skyrmions are demonstrated aiming at the design principles of skyrmionic memory
devices.
