In the equal temperament tuning system, the octave is divided into exactly twelve notes. The distance between each note is called a half step. On the keyboard, each key is a half step away from the next and previous keys:

One whole step contains two half steps. All white keys on the keyboard that are separated by a black key are one whole step apart. The keys that are not separated by a black key are half a step apart:

The notes corresponding to the white keys on the keyboard are designated C, D, E, F, G, A, and B. These can be raised by half a step with a sharp or lowered with a flat. A black key, such as the one between C and D, can be considered a C sharp or a D flat:

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