Space-time is a concept that combines the three dimensions of space (length, width, and height) with the dimension of time into a single four-dimensional continuum. It's a fundamental concept in physics, particularly in Einstein's theory of general relativity.

In classical physics, space and time were considered separate entities, with space described by the three dimensions of length, width, and height, and time treated as a separate dimension progressing uniformly forward. However, Einstein's theory of general relativity revolutionized this understanding by proposing that space and time are intimately connected in a single fabric called space-time.

In the framework of general relativity, massive objects like stars and planets warp the fabric of space-time around them, causing what we perceive as gravity. This warping of space-time is often visualized as a bending or curvature of the fabric. Objects moving through this curved space-time follow paths determined by this curvature, leading to the motion we observe in the universe.

Space-time is not just a static stage on which events occur; it is dynamic and influenced by the distribution of matter and energy within it. This dynamic nature is crucial for understanding phenomena like gravitational waves, black holes, and the expanding universe.

In summary, space-time is the four-dimensional framework in which all events occur, integrating the three dimensions of space with the dimension of time into a unified whole, as described by Einstein's theory of general relativity.