Guide Fingers are fingers which remain on the same string, but move to a different fret.  They are helpful because
they provide a physical vehicle to move from one position to another, guaranteeing that the guide finger will end up (stay) on the correct string.  Guide fingers are indicated by a hash mark in front of the finger number.


Example 1

Notice how the third finger has traveled from the D on the last beat of first measure to the E on the first beat of the second measure.  A guide finger is again employed when the third finger travels back to the D on the second beat.



Guide Fingers may also be useful when changing from one chord to another. 
In the following example, note that both chords have the first finger on the 3rd string.

Example 2

To pass from the E to the D, remove the second and third fingers, leaving only the first finger on the third string. 
Now, guide the first finger from the first fret to the second. 
Finally, form the rest of the D with the second and third fingers.


Like Common Fingers, we can also create guide fingers if we get a little creative (no pun intended).

In Example 3A, these two chords have no opportunity for a guide finger:

Example 3A

But if we re-finger the D, we can create a guide finger on the first string:

Example 3B

Now, to change chords from the D to the G, clear the second and fourth fingers
and guide the third finger from the second fret to the third. 
Finally, form the rest of the G chord with the first and second fingers.