This is the "G Clef" or " Treble Clef." This is used for higher voices
This is the "Modified G Clef"
The 8 attached to the bottom means it is 8 notes, or one octave below a normal G Clef,
An 8 above would mean the inverse. This is used mostly for the tenor voice to substitute for the C Clef.
This is the "C Clef" or "Tenor Clef" and was primarily used for the tenor voice until proven obsolete and is now used for Viola.. (I put it up for fun!)
This is an "F Clef" or a "Bass Clef." This is used for low voices