These lecture notes provide a tutorial review of non‎-Abelian discrete groups and show some applications to issues in physics where discrete symmetries constitute an important principle for model building in particle physics‎.‎ While Abelian discrete symmetries are often imposed in order to control couplings for particle physics ‎- in particular model building beyond the standard model ‎- non‎-Abelian discrete symmetries have been applied to understand the three‎-generation flavor structure in particular‎.‎ Indeed‎,‎ non‎-Abelian discrete symmetries are considered to be the most attractive choice for the flavor sector‎:‎ model builders have tried to derive experimental values of quark and lepton masses‎,‎ and mixing angles by assuming non‎-Abelian discrete flavor symmetries of quarks and leptons‎,‎ yet‎,‎ lepton mixing has already been intensively discussed in this context‎,‎ as well‎.‎ The possible origins of the non‎-Abelian discrete symmetry for flavors is another topic of interest‎,‎ as they can arise from an underlying theory ‎- e‎.‎g‎.‎ the string theory or compactification‎.‎‎.‎‎.‎