What makes a note a half step higher?

A note is a half step higher when it is one semitone above its original pitch. In Western music, this typically involves moving to the next adjacent key on a piano keyboard—either to the right (for sharping a note) or to the left (for flatting a note). For example, moving from C to C# or from E to Eb represents a half step increase. This interval is the smallest in Western music, creating a subtle but distinct change in pitch.