Greek letters

Letters in the Greek alphabet are used sometimes in mathematics and physics in addition to the familiar Latin alphabet (Aa, Bb, Cc, etc.) to provide additional symbols to help make it easier to distinguish different concepts. You are likely already familiar with the Greek letter $\pi$ (pi).

Below is a reference table of some of the most common letters in the Greek alphabet used in mathematics. To see all of the letters of the Greek alphabet as well as the case-variants I have omitted from the table above, click here.

Upper-Case	Lower-Case	Name	Most common use(s) in mathematics	Most common use(s) in physics
	$\alpha$	alpha	angle measures	angular acceleration
	$\beta$	beta	angle measures	the speed of an object divided by the speed of light $\beta =\frac{v}{c}$
$\Delta$	$\delta$	delta	change of a variable (upper case), a small quantity (lower case)
	$ϵ$ or $\epsilon$	epsilon	a small quantity	electric permittivity
	$\theta$	theta	angle measures
	$\lambda$	lambda		wavelength, linear density
	$\mu$	mu		micro (SI prefix for $10^{-6}$), coefficient of friction, magnetic permeability
$\Pi$	$\pi$	pi	the ratio of a circle’s circumference to its diameter $\pi \approx 3.14$ (lower case)	a product of a sequence (upper case)
	$\rho$	rho		volume density, electrical resistivity
$\Sigma$	$\sigma$	sigma	a summation (upper case)	area density (lower case)
	$\tau$	tau	the ratio of a circle’s circumference to its radius $\tau =2\pi \approx 6.18$	torque
	$\varphi$ or $\phi$	phi	angle measures
$\Psi$	$\psi$	psi		quantum state, quantum wavefunction
	$\omega$	omega		angular frequency, angular velocity/speed