We introduce the algebraic structures in particular groups. Groups and their fundamental properties. Subgroups and cosets. Group homomorphisms. Normal subgroups and factor groups. Cyclic groups, linear groups, permutation groups. Lagrange's Theorem, commutators and commutator subgroup. Direct products. Group actions: stabilizers, orbits, transitivity, regularity, Cayley's Theorem. p-groups and Sylow's Theorem. Endomorfisms of cyclic groups and automorfisms of a cyclic groups.