The Greek alphabet (/ˈgri:k ˈælfəbet/) is an alphabet used to write Greek languages, particularly Ancient Greek and Modern Greek.
The 24 letters of this alphabet are Α α, Β β, Γ γ, Δ δ, Ε ε, Ζ ζ, Η η, Θ θ, Ι ι, Κ κ, Λ λ, Μ μ, Ν ν, Ξ ξ, Ο ο, Π π, Ρ ρ, Σ σ/ς, Τ τ, Υ υ, Φ φ, Χ χ, Ψ ψ, and Ω ω.
That is, alpha, beta, gamma, delta, epsilon, zeta, eta, theta, iota, kappa, lambda, mu, nu, xi, omicron, pi, rho, sigma, tau, upsilon, phi, chi, psi, and omega.
The Greek alphabet is the ancestor of the Latin alphabet, and some letters are recognisably similar. Not being able to read Greek however is the origin of the English idiom "it's (all) Greek to me"!
In English, Greek letters are sometimes used (1) in scientific nomenclature, e.g. β-carotene, γ-ray, or(2) statistics, where Greek letter represents a statistic and a Latin letter a parameter (3) in linguistics texts where the audience is assumed to understand Greek.