The spinning jenny functions through the use of a hand crank and multiple spools of thread instead of just one. It was a multispindle spinning machine invented by James Hargreaves in 1764, and It facilitated the production of yarn because the user could simultaneously handle eight or more spools.
The spinning jenny consisted of a metal frame with eight wooden spindles at one end. The frame also had a beam that had a set of eight rovings, narrow and long bundles of fibers, attached to it. When the rovings were extended, they passed through two horizontal wooden bars that could come together. These bars could then be drawn along the frame’s top by the spinner’s left hand, which allowed the thread to be extended. Meanwhile, the spinner's right hand was used to quickly turn a wheel. This action caused all of the spindles to turn, resulting in spun thread. When the bars returned to their original places, the thread was wound onto the spindle. A pressing wire, called a faller, was used to keep the threads in the correct locations on the spindle.
In 1733, James Kay’s invention of the flying shuttle increased the demand for yarn by doubling weavers' productivity. Hargreaves's invention responded to the demand by allowing spinners to be much more productive. In 1770, James Hargreaves had his sixteen-spindle spinning jenny patented. Some later models of the spinning jenny boasted up to 120 spindles. The spinning jenny decreased the need for labor and facilitated cotton production.