Meshes are a key ingredient to perform computer simulations with unstructured methods such as the finite element method and the finite volume method. Mesh generation aims to decompose highly complicated domains by filling them with distributions of different types of elements such as triangles, quadrilaterals, hexahedra, tetrahedra, pyramids, and prisms. This geometrical decompositions, referred as mesh, are used to approximate the computational domain and the Partial Differential Equation (PDE) solution. The size of the mesh elements can be locally adapted to obtain more accurate approximations to the PDE solution.