Musicians and vocalists use the treble clef, also known as the G clef, for higher-pitched notes. It's centered on the second line of the staff, which represents the G note above the middle C note.

There are many different mnemonics that can be used to remember the notes on the alto clef (reading from the bottom line up). You could use this mnemonic to remember the notes on the lines: You ...

It is also possible to extend above and below the stave ... as they play lower pitched notes, where a guitarist would use the treble clef. It's worth noting that there are several other clefs ...