This textbook explores both the theoretical foundations of the Finite Volume Method (FVM) and its applications in Computational Fluid Dynamics (CFD). Readers will discover a comprehensive explanation of FVM numerics and the algorithms used for simulating incompressible and compressible flows, as well as a detailed examination of the components necessary for developing a collocated, unstructured, pressure-based CFD solver. Two specific CFD codes are covered. The first is uFVM, a three-dimensional, unstructured, pressure-based, academic CFD code implemented in Matlab. The second is OpenFOAM, an open-source framework used in the development of a variety of CFD programs for simulating flow problems on an industrial scale. With over 220 figures, numerous examples, and more than one hundred exercises on FVM numerics, programming, and applications, this textbook is suitable for readers seeking a comprehensive understanding of the subject.