Every human endeavor has its own particular vocabulary: an artist speaks of color, tone, composition, lighting, and texture; psychologists consider perception, behavior, emotion, personality, and more; a mechanical engineer must attend to principles of friction, work, energy, stress, strain, and pressure. So it is with computing. Even though the field is expansive, there are a small number of common concepts at its core. Here, we have some most important ideas that decorate the landscape of computing.