The three different periods of Beethoven's work are as follows:
A formative period that extends to 1802- this was the period where he first started and grew to develop his music . A middle period from 1803 to 1814- this was the period where he wrote the famous piece Moonlight Sonata and Piano Sonata in E. Minor, Op 90
A mature period from 1814 to 1827- this was the period where he proceeded to write more of his mature works until he died in 1827.
Step-by-step explanation:
1779 to1802 - formed first two symphonies.
1803 to 1814 - put collectively language and musical techniques.
1815 to1827 - passionate about being emotional and individual