Determining the Key
The key signature is placed after the time signature indicating the key or pitch range of the scaling system for the appropriate instrument with a series of sharp or flat signs. Depending upon the key, the signature could contain one or several sharp or flat symbols. See also Keys and Chords and Chromatic Intervals for key breakdown, assignment, and reference.
Key Marks & Accidentals
Key Marks, also called Accidentals or Key Symbols are placed next to the note when changing its pitch during the composition. The natural key symbol is never used in the key signature. Illustrated below are the key marks.