Understanding the basics : Notes

Before you really start understanding guitar you need to know a little bit about how music works (commonly called Music Theory). I am going to explain what notes are and how they work. This will help you understand later lessons that go deep in into music theory.
Here is the definition of a note from dictionary.com: Note- a sign or character used to represent a tone, its position and form indicating the pitch and duration of the tone.

Notes are the building block of music. They can be played one at a time to form a melody, or they can be played in unison to form a harmony. Melody and harmony are the backbone of any good musical piece. [Melody is a group of notes played one after the other. Harmony is a group of notes played at the same time]. All scales and chords are made out of notes. There are twelve notes in western music (some Asian and African cultures have extra notes in their music, but it is not relevant for our purposes). Those notes are:
The “#” is pronounced “Sharp” and “b” is pronounced flat:

The distance between one not is called a Half-Step. So from A to A# is a half step. The # sign means one half-step up. So A# is one half-step up from A. Thus D# is one half step up from D. But E is WHOLE-STEP up from D. (because two half-steps = a whole-step. So D to D# is a half-step and D# to E is another half-step. That equals one whole step from D to E).
The “b” sign means you go DOWN one half-step. So Gb is one half-step below A. Db is one half-step below D.
The reason I put a red box around some notes is because those notes are the same note, just with a different name. So A# is the same is Bb because A# is one half-step up from A and Bb is one half-step down from B. Thus the notes sound the same. We will get into the reasons later as to why it would be called A# vs. Bb and visa versa. Notes that sound the same but have different names are called enharmonic notes. So Ab and G# are enharmonic.
Don’t worry about it for now.
Also notice that the notes B and C as well as E and F have no sharps or flats between them. This there is no such notes as B# (same note as C), Cb (same note as B), E# (same not as F), and Fb (same not as E)
I know this may seem a little confusing at first. Just make sure you follow along with the graphic of the notes.