The # sign (approximated), also known as the sharp can appear amid a song (an accidental), or in the key signature. Any note that falls on the note modified by the sharp will cause any previous accidental or key signature (for that note) to be considered moot and the new, sharped, value to take its place. The value is then raised a half-step harmonically.
For example:
- C becomes C# (which is enharmonically the same as a Db).
- Db becomes a D# (which is the same as Eb)
- E becomes E# (which is the same as F)
And so on.