General Theory of relativity as of today gives the best explanation of gravity, universe and space-time. The development of general relativity began with equivalence principle which means while standing on the surface of earth, the state of a person being at rest and also at accelerated motion are physically identical which means they are same with respect to one another.

Videos of the series---
1. All about gravity--- https://youtu.be/7CeNjYzpmgM
2. Space-Time Mystery explained--- https://youtu.be/s7VbXhD73bQ
3. How does special relativity works?--- https://youtu.be/fIQAHRw5mgg
4. General Theory of relativity, a myth or reality?--- https://youtu.be/y4Se7ld1ppc

In classical mechanics and special theory of relativity, it is said that inertially moving objects cannot accelerate with respect to each other but objects in free fall do so which was contradicting with reality. So Einstein proposed that Spacetime is curved in General theory of relativity and thus explained many phenomenon of the universe.
So let’s now see some of the phenomenon which was explained by general theory of relativity.