Common Sense Relativity and Spacetime

Based on simple, common-sense observations, the author introduces spacetime in an easily understandable way. Concepts in and around spacetime are explained first independently of any kind of 'relativity connotation', then in the nonrelativistic context and finally in the special relativistic context.Reference frames, while traditionally foundational, make reasoning about spacetime unnecessarily particular. Thinking in terms of spacetime itself makes us much more confident and creative and this carries over to other branches of physics as spacetime is the stage where 'physics happens'.  The consistent mathematical formalism of the textbook is as simple as possible and close to the everyday practice of physicists. It helps readers realize that precise mathematical formulation avoids paradoxes and, in general, it is a valuable guide towards the better understanding of Nature.