Sharp
also called: sharp sign
The two-crossed-lines sign before a note (or in a name like F♯) raising its pitch by a half step.
What you do
Play the note one half step higher — the very next key or fret up. Placed before a note, it lasts for the rest of that measure on that line or space, and the barline cancels it — with one classic exception; a sharped note TIED across the barline keeps its raised pitch for the tied note, though any later restruck notes in the new measure revert. Parked at the start of the line in the key signature, it applies to every note with that letter name until the key changes.
Don’t confuse with
The double sharp is a compact x-like cross, not the open grid — it raises the note TWO half steps.
The natural sign (a lopsided open rectangle with stems) CANCELS a sharp or flat; it looks boxier and has only two vertical strokes with no grid.
See also
flat · natural · key-signature
For specialists
SMuFL: accidentalSharp
Record status: draft — verification pending (bookshelf locators + chord-symbol authority; OQ-1 blocks the slice gate)