Today we are going to talk about interval.
Interval is simply the distance between 2 notes. As you can see on the keyboard in your house, there are white pieces and black pieces. So how we measure the distance between notes?
First, you must know the distance between 2 adjacent pieces is half tone or semi tone. Or in other words, distance between neighboring black and white pieces is semi tone.
Long story short, as you can see on the keyboard, the distance between C and D is 2 semi tone (because there is a black piece in between) or we call it tone. This interval is same with other neighboring white pieces (D to E, F to G, G to A, and A to B). Be careful for E to F and B to C. Because there is no black piece in between, so their distance must be semi tone.
To summarize this, the scale C D E F G A B Chas the following pattern of interval :
C (Tone) D (Tone) E (Semi tone) F (Tone) G (Tone) A (Tone) B (Semi tone) C or T T S T T T S for short.
Remember this pattern, because we are going to talk about Major scale next time!
Musicluster 
There are 36 seven note scales comprising notes with different letter names. Each scale has its own set of diatonic chords and its own set of modal permutations (some of which duplicate scales already familiar to us). It’s a rich source of musical material. Using 1 = eighth note (quaver) and 2 = quarter note (crotchet) is a useful way of comparing scales. Major scale = 2212221 etc… Keep up the good work.
Thank you for you comment. It is indeed sipler to be understood using 2212221 pattern. It is just a matter of explanation style. I just want to make it univarsal using the term tone and semitone
Absolutely nothing wrong with doing things your way. I mentioned the numerical system because it fits into other areas so nicely where numbers can be used to speed up and simplify our work. Time is money to a pro. Thanks for your input, JM.
I should say thaks too. I should study more and convey things more efficiently. Thanks for the input