The term note has two closely related meanings in a music context. One is a sound's pitch (how low or high it sounds to human ears). The other is the representation of a pitch together with its duration in standard music notation.
Most Western music employs a standardized set of pitches as well as a standardized notation for them and their durations. The seven main pitches in the commonly used chromatic scale (i.e., the white keys in an octave on a piano) are represented in speech and text by the letters C, D, E, F, G, A and B, and the remaining five (the black keys) are represented by one of these letters followed by the word or symbol for sharp or flat, which raises or lowers the pitch by a half step. The corresponding notes inclusive of their durations are represented in standard music notation by the familiar note symbols, with the vertical position of each note on the staff (set of five parallel horizontal lines) indicating its pitch, and its form (i.e., whether the oval section is white or black, whether it has a stem, and the number of flags, if any) showing its duration.