In music notation, a sixty-fourth note represents one-sixteenth of a beat and is represented by a filled circle with a stem and four flags or beams. It is so named because it lasts for the duration of one sixty-fourth of a whole note. Also called a hemidemisemiquaver.
A series of sixty-fourth notes on the staff looks something like this:
/\
---| /-----------------------------|\----------------------
|/ |\ |\|\
---/-----------------|\-------*----|\|\|\------------------
/| * |\ *| |\|\|\|
-/-|/\--------/|-----|\----|-|-----|-|\|\|-----------------
| | | \| |/ |/| * | |\|
|--|--|-------\|----*------|/|------*--|-|-----------------
\ | | \| |/| * |
--\|_/--------\|-----------|/-----------*------------------
|
\|