The Classical period in Western classical music lasted from around 1750 (when Bach died) to around 1825 (shortly before Beethoven's death in 1827).
During this period, orchestras increased in size and were established as having a woodwind section, a string section, a brass section, and a percussion session, which is how orchestras are organized to this day. The piano was a relatively new invention which allowed playing notes softly or loudly depending on how hard you press the piano keys, unlike harpsichords which could only play at one volume. Composers wrote numerous piano trios and sonatas, and they experimented with using a variety of musical keys and melodies and rhythms and dynamics (how loudly or softly the notes are played) within a piece.
The Agricultural Revolution and the Industrial Revolution in the 1700's led to the rise of a "middle class." This was a group of people who earned their wealth, placing them in between the aristocracy (who inherited their wealth) and the peasants (who had no wealth). The world was changing, and these changes are reflected in the music of this period. Middle class people wanted to be educated, and they wanted to enjoy their leisure time. Music is a rewarding way to spend one's leisure time, so middle class children were taught to read music and sing and play instruments. After a hard day at work, the middle class wanted to relax and enjoy their entertainment, so they didn't want to hear intellectually-demanding music which required a lot of focus and attention and thought. They wanted music which was easy to listen to and which they or their children could perform without needing to devote years of practice. Therefore, music during the Classical period was designed to have melodies which would immediately appeal to the listener, as opposed to the intricate and complex polyphonic music of the earlier
The middle class tended to prefer homophonic music, which features a melody plus an accompanying harmony. In addition, the middle class wanted music which expressed a moderate amount of emotion without going beyond what was considered dignified and proper for polite society.
Another consequence of the rise of the middle class was a concern for social reform, which led to a longing for humanitarian ideals and the concept of "the brotherhood of man." This influenced composers to write music which could be enjoyed by anyone, anywhere, because the music minimized any national differences and emphasized elements which were common to all people. The goal was for music to have universal appeal no matter what country it was performed in, not being too difficult for the average listener to follow, yet allowing people to enjoy a sense of refinement and elegance.
These are some of the composers of this period, and a taste of their music. I tried to select well-known pieces, but in many cases I had to pick something at random from what's available in YouTube. Where possible, I chose videos which show live performances of the pieces. The links will take you to the Wikipedia pages for the composers and their works.
The names of many of these pieces are followed by a number which is based on a catalog of the composer's works, such as "Op. 67" or "BWV 1046-1051." See the
page for more on these catalogs.
The Wikipedia article says: "When the symphony was written, Haydn's patron Prince Nikolaus Esterházy was resident, together with all his musicians and retinue, at his favorite summer palace at Eszterháza in rural Hungary. The stay there had been longer than expected, and most of the musicians had been forced to leave their wives back at home in Eisenstadt, about a day's journey away. Longing to return, the musicians appealed to their Kapellmeister for help. The diplomatic Haydn, instead of making a direct appeal, put his request into the music of the symphony: during the final adagio each musician stops playing, snuffs out the candle on his music stand, and leaves in turn, so that at the end, there are just two muted violins left (played by Haydn himself and his concertmaster, Luigi Tomasini). Esterházy seems to have understood the message: the court returned to Eisenstadt the day following the performance."