Tonality is an organized musical composition of one central tone and the remaining other tones have a relationship with that root tone.

We must know the Scale (The tones of the Major and Minor scale ) in order to understand the Tonality.

The word scale is derived from the Latin word scala. A scale is a step-wise series of notes. It’s theoretically the eight consecutive notes (A B C D E F G A), that start at a particular note, then go up or down the keyboard, until get back to the same letter.  Scales were first found in the musical ideas of Ancient Greek. Later in the 16th century, in the West the scale dominate music-making. At this time Ionian is assumed as the major scale, whereas Aeonian is the natural minor scale. Tonality, in music, is the principle of organizing musical compositions around a central note. It signifies the specific system of relationships between notes, chords, and keys.