Wormholes are actually hypothetical, meaning nobody knows whether or not they exist. You’ve seen the movies, a guy in a spaceship flies into a black hole, and is pulled through a glowing tunnel into a different time and a different place. While this is somewhat of a guess, it is partially true to known theory. A wormhole is a rip in the space-time continuum, appearing in a specific time and place. All humans can do about wormholes is theorize, as nobody knows if they actually exist, therefore not having any test subjects. There are different types of universes, and these end up in different places.

An intra-universe wormhole is a wormhole that leads to a different place in the same universe. This works by creating a shortcut through spacetime, which can be demonstrated by bending a cloth. If you normally are staying on the cloth, a wormhole would be folding the cloth, and connecting two parallel points on the cloth. Hypothetically, any type of wormhole would only be existent for an instant. The time a wormhole exists is equivalent to the period of time that is passing in a movie when you pause it. It is most likely existent for such a short period of time that you would have to pause time at the exact right moment to see it. 

A wormhole that will lead to a different universe is usually called a Schwarzchild-wormhole. Let me talk about string theory for a bit, because it will be easier for you to understand if I you knew String Theory. In string theory, everything in our physical and psicological universe is made up of tiny vibrating strings of energy. Anything contained to one universe is a two-ended string, tied down to a string stretched out by the eleventh dimension (if confused, just wait,) called a brane. No, not brain, brane. Brane is short for Membrane. Now in String Theory, There are the three dimensions we enjoy, time, and six dimensions that are to specific to be noticed by the eye. That makes a total of ten dimensions, but I said that there was eleven. This eleventh dimension came in when the scientists realized that string theory needed one more dimension to work, and this was the eleventh. A Schwarzchild-wormhole is a wormhole leading to a different brane. To travel to another universe, you would have to change your string-type. You would have to have your strings broken off the brane, and then they would have to be converted into a circular string to travel across the wormhole, and then turned into straight strings again, and be tied down onto the next universe. Since the timestream is actually different, and they are not experiencing the same time, you would end up in a random place at a random time. You could end up at the center of a planet while it is forming, or you could end up at a tropical planet, a thousand year later than option 1.

For more science, read String Theory, Not Spaghetti.