The treble clef staff and bass clef staff are often joined together to form a Grand Staff or great staff.
To review Treble and Bass Clefs see The Treble Clef and The Bass Clef.
The two staves are joined by a vertical line on the left side and either a brace { or a bracket [.
A bracket is used when there are two or more similar instruments playing together, such as two flutes or two trumpets.
A brace is used when both staves are to be played by the same instrument such as a piano or harp.
Middle C is the note that is one ledger line below the treble clef and also one ledger line above the bass clef. They are both the same pitch.