Harmonicas or harps probably are the most-built instruments in the world and because they are small and relatively easy to learn they are maybe even the most popular ones.
The sound is generated with swinging metal reeds, similar to accordions. The air that flows inside the instrument puts these reeds in motion and produces different tone pitches depending on the gauge and the length of the reed. The reeds of harmonicas are arranged on a so-called reed plate. There are two different kinds of tongues: blow reeds that are stimulated through blowing and draw reeds that sound through sucking the air in.
The harp was invented in the 1820s. However there were earlier models like the Chinese “Zeng” which is made of bamboo and that already exists for more than 5000 years. The different construction types that are popular today support diverse techniques and are played in various music styles. For beginners especially the blues harp is suitable.