This comprehensive exploration of a metric approach to some relevant problems and techniques in analysis focuses on examining spaces of homogeneous type. Both the structural and analytical problems under consideration reflect very active areas of current research. The exposition, motivated by examples and details of which many cannot be found elsewhere in book form, unfolds systematically in three parts, starting from such preliminaries as the basic structures of quasi-metric spaces, the homogeneity property and measure theory. More advanced topics are then covered, including Caldersn-Zygmund decompositions, L^2 techniques, weighted norm inequalities, BMO, and Hardy spaces. The final aim is to encourage a well-developed way of thinking about some mathematical and even physical problems, i.e. Newtonian and Riesz potentials, fields and their derivatives, mean value and Harnack inequalities related to Hvlder regularity, wavelet type analysis on non-euclidian contexts, etc. The book is suitable for self-study or as a classroom resource for graduate students in analysis and PDEs. Real analysis and topology, some basics of Fourier analysis and PDEs are requisite background for the reader.