The Complete Idiot''s Guide to Music Theory

Marking
Means …
D.C. al Fine
Go back to the beginning and play through to the end.
D.C. al Coda
Go back to the beginning and play to the Coda sign; then
skip to the Coda section.
D.S. al Fine
Go back to the Segno sign and play through to the end.
D.S. al Coda
Go back to the Segno sign and play to the Coda sign; then
skip to the Coda section.
85
“D.S.” is short for
Dal Segno
, which means
“from the Segno” (or, in
English, “from the sign”).
“D.C.” is short for 
Dal
Capo
, which means “from
the head” or “from the
start.” (
Capo
is Italian for
“head”—literally, the top
of the chart.)
Definition
Use the Segno (left) and Coda (right) signs to navigate a piece of music.
Repeating Measures
If you have only a single measure to repeat, you can use a 
measure repeat
sign.
Just insert this sign between the bar lines 
after
the measure you want to repeat;
musicians will know to repeat the previous measure.
Use the measure repeat sign to repeat the contents of the previous measure.
You can use the measure repeat sign in multiple measures. For example, if you
have three measures worth of repeat signs, you play the original measure four
times (the original time plus three repeats).
Repeating Notes
If you’re really lazy, you’ll like the fact that you don’t always have to write each
individual note in a piece of music. If you’re repeating notes of the same rhyth-
mic value and pitch, you can use 
note repeat
notation to spare yourself the trou-
ble of writing down all those eighth or sixteenth notes in a row.

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Part 2:
Rhythms
Note repeats are indicated by drawing slash notes through the main note. One
slash mark means play two notes in a row; each equal to half the value of the
original note. For example, if you draw a single slash through a quarter note,
you play two eighth notes; a single slash through an eighth note means you play
two sixteenth notes.
Two
slash marks means you play 
four
notes in a row; each equal to one quarter
the value of the original note. For example, if you draw a double slash through
a quarter note, you play four sixteenth notes; a double slash through an eighth
note means you play four thirty-second notes. The following table indicates
some common note repeat values.
Note Repeat Markings