Nether Portals are structures that are automatically generated that allow a player to travel between two of the dimensions: Overworld and Nether. Here is an intelligent calculator that allows for the placement of portals accurately at the proper coordinates in the Overworld and Nether dimensions.
The Nether is good for speeding up a journey in the overworld, when you discover how fun Minecraft is! There’s a trick though: You have to pair your gates. Using this calculator, you’ll be able to do that.
It’s common to appear in a place you weren’t expecting when stepping through a portal if you’re in a world with others using the nether.
Once, by stepping through a portal for someone else’s gate room I appeared in their home at XYZ. I understood nothing when I got back through, and I was standing in a room blown to pieces by some creeper, it was dark, and I didn’t recognize anything. I fell into a chasm while trying to find my gate while I was panting and panicking and ended up dying, so I scrambled around, trying to avoid phantoms and angry mob babies.
Building a gate becomes easier if you have your XYZ coordinates available when building it, along with flint and obsidian to assure a return gate (if needed). To avoid getting attacked or burned by lava flows or a fall, I build a quick enclosure around each new gate as I make my way into the nether.
When I get my XYZ back in place, I review my XYZ to see if I should explore different portals in order to build my own.
I usually use that same trick even in places where I am on my own, so that I can locate where my gates are when I am mapping what is overworld to my nether-highway.
It didn’t work? Sometimes the gates don’t line up the way you expect. If that happens, you may need to do more research to find out why it isn’t working properly. There have been times when I have encountered this problem, but it happens so infrequently I have stepped into a new gate in the process.