This guide will help you approach music directly, as opposed to approaching it from the point of view of any one particular instrument, helping you grow as a well rounded musician not just a specific instrument player, something that will help you expand your horizon.
The notes in the musical alphabet are:
A     A #      B      C       C#        D       D#        E         F      F#      G      G #
This pattern repeats itself, and is called the CHROMATIC SCALE

It consists of the “Natural” Notes
A   B  C  D  E  F  G
with the addition of “Accidental” notes
A#    C#    D#   F#  and  G#

What does the “#” symbol mean?
The “#” symbol is pronounced as “Sharp” in the music notation, and is considered a half tone(Immediately next note) above the intended natural note. “A#” for instance, is the intermediate note between A and B, the next note after A.
In the musical alphabet, B# and E# don’t exist, and the immediately next note for B is C, and for E is F directly, without any intermediate. Please see the piano correlation to understand how this works out.
The musical Inverse of “sharp”, is “flat” and is denoted by “b”. A# can be represented as Bb(pronounced B flat). Similarly, C# can be represented as Db.
After the G# note, the pattern starts repeating itself indefinitely.
In physics, each one of these notes represent a particular frequency, which doubles itself in it’s next manifestation. To elaborate, lets take two instances of the above pattern, in sequence:
A    A #    B   C    C#    D   D#   E   F   F#   G   G #   A    A #    B   C    C#    D   D#   E   F  F#   G G #
In this example, the second occurrence of the A note is double the frequency of the first A note, And the same goes for all the other notes present here. The second occurrence of the initial note, is called the “Octave” of the note. If you were to take this pattern and repeat it for five times, then the fifth occurrence of the same note would be the “fifth octave” of the note.
 
It is common practice to initiate this pattern from C to C instead of A to A, although it’s a full circle either ways.  Have you ever wondered why the notes on a piano are arranged the way they are?
Like many things in music, there is logic behind that too. Although this guide is meant to be general, we’re using a piano’s keys(something we’ve all seen) to elaborate the points mentioned.
All the white keys on a keyboard represent the “Pure” (natural) notes as opposed to notes that are sharpened or flattened versions of the natural notes(accidentals). The black keys, ofcourse, are the accidentals.
 
 
Take a look at the figure:

Figure: The notes on a piano.
As visible in the figure,  The White keys denote natural notes and the black keys denote accidentals.
TONES AND SEMITONES
After the concept of notes has been established, logic dictates there must be some unit step between two sequentially occurring  notes. Taking our piano diagram into consideration again:

 
Semitone is the gap between a note and the immediately next tone in the chromatic scale. In the example mentioned here C# is a semitone above C and similarly, F is a semitone above E (as there is no E#)
Some more examples:
Semitone above B is C
semitone above: G# is A (as chromatic scale repeats itself after G#)
TONES(not to be confused with Tonality)
Tones are twice the gap of semitones which means, Two Semitones Make up a Tone. A tone is also referred to as Whole tone or Full tone.

Examples of Whole Tones:
F# is a tone above E
G is a tone above F
B is a tone above A
D is a Tone above C
 
Chords are built from scales, and scales are built from notes. The understanding of the musical notes thus becomes a critical step to understand these aspects of music.
 
We strongly suggest you continue to a study of SCALES to put the knowledge of notes into perspective. Feel free to hit us up with any questions that you might have, in the comments section below.