Aimed at readers with some mathematical background, the work explains the principles and consequences of both the special and general theories of relativity without heavy formalism. It reexamines space, time, simultaneity, and coordinate systems to introduce the Lorentz transformation and the resulting behavior of moving clocks and measuring rods, including velocity addition. It then develops the equivalence principle and presents gravity as a manifestation of spacetime geometry, outlines the qualitative form of the gravitational field equations, and surveys empirical tests and observable implications for light propagation and planetary motion, with diagrams and appendices to clarify key points.