Resumen: The present End-of-Degree Thesis is framed within the context of Majorana fermions in Condensed Matter, and it focusses on the Rashba nanowire, a realistic system which allows the emergence of Majorana zero modes. After having introduced the present state of affairs in the field, the original proposal is reviewed, and subsequently, a nanowire with inhomogeneous spin-orbit coupling is analysed. Utilizing numerical techniques, it is shown that under precise conditions a defect in the spin-orbit coupling can originate zero-energy fermionic bound states akin to the original Majorana zero modes. Finally, a finite-size effect induced by the presence of the defect is investigated.