(You might want to read about the Staff before you read about the Alto and Tenor Clefs.)
The Alto and Tenor Clefs have two curves that meet in the center. The line on the staff where these curves meet is the note C. These clefs are also called C Clefs for this reason.
The Alto Clef is positioned on the middle line. This line becomes the note C. (This note is also Middle C.)
The note names in Alto Clef are:
Tenor Clef is very similar to Alto Clef but the main difference is that the Tenor Clef is positioned on the second line from the top whereas Alto Clef is positioned on the middle line. In Tenor Clef the second line from the top becomes the note C. (This is also Middle C, just like in Alto Clef.) 
The note names in Tenor Clef are:
The note names in Tenor Clef are:Learn about the Treble and Bass Clefs
