Up to this point, we have been playing the seven notes of the C major scale: C-D-E-F-G-A-B. Additional notes may be created by lowering or raising the pitch of these tones with symbols called accidentals.
Blues Ninja 'o Leeward | Peter Kun Frary
Accidental Symbols
To indicate raising or lowering of pitch, an accidental is placed on the note's left side. The sharp, flat, and natural are the most common accidentals:
Sharp
Flat
Natural
raises half step
lowers half step
cancels/restores
How to Say It
Speak the letter name of the note followed by the accidental: A-sharp, B-flat, D-natural, etc.
Accidentals for Beginning Guitar | Peter Kun Frary
Playing Accidentals
What is a Half Step?
A half step is the smallest interval (space) between notes. To hear a half step, play notes on adjacent frets on the same string or sing ti to do in the major scale.
Half Step | A one fret movement along the same string.
Sharp () | Raises Pitch
The sharp symbol raises a note's pitch by a half step—a shift of one fret higher. In the example below, the first note, G, is normally played on the open third string. The second note, G-sharp, is a half step higher in pitch—one fret—and thus played on the first fret of the third string.
Effect of Sharp Symbols
Flat () | Lowers Pitch
The flat lowers a note’s pitch by a half step—a shift of one fret lower. Thus, the first note in the example below is D. Normally D is played on the third fret of the second string. The second note, D-flat, is a half step lower in pitch—one fret—and thus played on the second fret of the second string.
Effect of Flat Symbols
Natural ()| Cancels a Prior Accidental
Theelectric bolt symbol is a natural. The natural cancels a prior sharp or flat. In other words, it restores a note to its original pitch. In the first measure below, the natural on the second beat cancels out the prior flat, restoring the second beat to D-natural.
Effect of Natural Symbols
Another Way to Look at It
You may find it helpful to think of accidentals in relation to the guitar's body:
Sharp (): shifts the note one fret towards the body—to the right.
Flat (): shifts the note one fret away from the body—towards the tuning keys or to the left.
Guitar Directions | Viewed from the player's perspective: sharps—higher in pitch—go to the right and flats—lower in pitch—go to the left.
Open String Flats
The notes E and B are normally played on the open first and second strings. What if you need to flat an open string? To flat an open string, the next lower string is used. For example, E-flat is on the fourth fret of the second string whereas B-flat is on the third fret of the third string:
Accidentals Within the Measure
When a note is altered by an accidental, later appearances of the same note within the measure are also altered. In the example, there's a C-sharp on beat 2. The C on beat 4 is also sharp because it is within the same measure, albeit not marked.
Altered notes automatically revert back to natural in the next measure.
Enharmonic Pitches
Some notes have the same pitch but different names. These types of notes are called enharmonic pitches. For example, C-sharp and D-flat are enharmonic pitches because they share the same pitch and fret position, but different names:
Enharmonic principles also apply to chords. For example, C-sharp 7 and D-flat 7 are the same chord.
TAB Musings
If you're reading TAB instead of notes, reading accidentals doesn't apply to you. Nevertheless, understanding accidentals is extremely useful. For example, a F chord becomes a F-sharp chord by sliding the chord shape up a fret. Tuner apps use sharp and flat symbols on their screens, so understanding these symbols is essential.
Click the blue forward arrow and begin working on your first piece with accidentals.
•••••
Playing Accidentals 
) | Raises Pitch
) | Lowers Pitch
) | Cancels a Prior Accidental
Another Way to Look at It 
Open String Flats
Enharmonic Pitches
TAB Musings
