What are accordion registers?

Registers are the switches that can be found next to the keys on the right hand side of the Accordion. There are usually anywhere from 3 to 11 registers on an accordion. By switching registers, it changes the reeds that are used and thus changes the sound. For example, one register might sound like a Clarinet and another might sound like a bassoon. Or you can have registers that are combinations of different registers. All of these produce different sounds and add more variety to the accordion.