In atomic physics and chemistry, **electron spin** is a property of an electron that is loosely related to its spin about an axis and its angular momentum. Two electron spin states are allowed, which are described by the quantum number *m _{s}*, with values of +½ or -½ .

The spin of an electron isn't as easily visualized as the spin of an ordinary object, such as a marble. Spin has a definite magnitude and it does have a direction, but quantization makes this more complicated than direction using regular vectors.

The SI unit of spin is the Newton meter second (N·m·s). This is the same unit as angular momentum in classical mechanics. However, spin is often calculated as the spin angular momentum divided by the reduced Planck constant *ħ*, yielding a dimensionless value.

## Uses

There are practical applications of electron spin. These include nuclear magnetic resonance (NMR), magnetic resonance imaging (MRI), electron spin resonance spectroscopy, and giant magnetoresistive (GMR) drive head technology.