Theoretically a Warmhole is a passage through Space-Time, which creates a shortcut to travel between two points in space-time which could reduce travel time and distance. Using General relativity Albert Einstein and Nathan Rosen proposed the existence of “Bridges” through Space-Time called Einstein-Rosen bridges or wormholes.
It is like, when we mark two points on a paper say A and B, now we want to go from A to B. Now join points A and B by folding the paper. This the concept of warmhole. Warmholes are to travel long distances in Space-time.
The video above explains more clearly.
Einstein’s theory of general relativity mathematically predicts the existence of wormholes, but none have been discovered to date. A negative mass wormhole might be spotted by the way its gravity affects light that passes by.
Certain solutions of general relativity allow for the existence of wormholes where the mouth of each is a Black hole. However, a naturally occurring black hole, formed by the collapse of a dying star, does not by itself create a wormhole.
Today’s technology is insufficient to enlarge or stabilize wormholes, even if they could be found. However, scientists continue to explore the concept as a method of space travel with the hope that technology will eventually be able to utilize them.