Notes may or may not have stems and flags. Note heads may be filled in, or the note will simply consist of an unfilled note head.
These different characteristics are used to indicate the duration of a note.
When stems are added to notes, it is important that they are written in the correct direction. Notes above the middle line on the staff, usually have their stems all written downward and on the left of the note head.
Notes that are below the middle line of the staff should have their stems written in an upward direction with their stems on the right side.
A note found on the middle line can have its stem go in either direction.
Flags are always added to the right side of the note.
When notes are joined, the stems will take the direction of the note that is the greatest distance from the middle line of the staff.