Answer:
Theme and variations is a very common musical structure you will come across, especially in classical music. The structure is built upon a musical idea called the theme which is played at the start of the piece. The theme can be as short as 8 bars in length or can be much longer. It usually consists of a memorable melody with an accompaniment of some sorts.
Once the theme has been played the composer then repeats it, but varies it in some way. This is called Variation 1.
Once Variation 1 has been played, the composer repeats the theme again, this time varying it in a different way, thus producing Variation 2.
This process is repeated as many times as the composer chooses producing a musical structure called Theme and Variations. Each variation is different, but can still be traced back to the original theme in some way.
Step-by-step explanation:
I hope this helps you :) sorry if it doesn't