127.0.0.1 or localhost, what is it?

Question

SSH

There are many different articles on the Internet that do not give me any idea at all about what it is. Everything is very superficial. I cannot understand how it works.
I am using the PuTTy program to connect to SSH.
There you can specify the Source Port and Destination? What is the source and destination port? I specify port 12345 and destination 127.0.0.1:12345. In proxifier, I specify localhost:12345 and I can connect to sites through a different IP. What is this address 127.0.0.1 anyway? I want to actually understand what sequence an http packet goes through. In the case of sending to a regular IP address, it is clear that the packet is sent to the set. fee, then to the router and then the router sends the packet to the right place. But I don’t understand what kind of mythical 127/8 it is. I don't understand things abstractly well, I need to understand them factually. I understand that a file is ones and zeros that are on the hard drive. Where is localhos actually located?)

Answer 1

127.0.0.1 is the network designation for your local computer, the one from which you are writing this message :)
localhost is a simplified designation for the same.