Ternary form is often used in popular music, folk music, and classical music. In popular music, it is often used in verse-chorus-verse (V-C-V) or verse-chorus-bridge-chorus (V-C-B-V) form. In folk music, it is often used in ballad form (A-B-C-B). In classical music, it is often used in sonata-allegro form (Exposition-Development-Recapitulation).
The following is a diagram of ternary form:
```
Exposition: Theme A - Theme B
Development: Theme A - Theme B - Theme A' - Theme B'
Recapitulation: Theme A - Theme B
```
In the exposition, the main themes of the piece are introduced. Theme A is usually in the tonic key, and Theme B is usually in a related key.
In the development, the themes are explored and expanded on. The development may go to different keys, and the themes may be varied or fragmented.
In the recapitulation, the themes are restated in their original order. The recapitulation may be exact or varied, and it may be in the tonic key or a different key.
Ternary form is a versatile musical form that can be used to create a wide variety of pieces of music. It is often used in popular, folk, and classical music, and it can be found in pieces from all over the world.