2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/203274We give an elementary introduction to the recent derivation of the effective low-energy gauge theories of D3-branes probing orientifolds of toric Calabi-Yau 3-fold singularities via brane tiling techniques.6 pages, 4 figures; typos corrected and reference added; contribution to the proceedings of the 3rd workshop of the RTN project 'Constituents, Fundamental Forces and Symmetries of the Universe', ValenciaHigh Energy Physics - Theorytext