I see all over here that it is required to torrent files. How is this the case? It is not clicking with me…
First you need to understand ports. Imagine your network traffic is like the postal service. Data gets placed into packets and then labeled with an ip header (encapsulation) some of that information will be to/from ip addresses and also port. The port identifies what the data is so it can go to the right place. Ex: port 80 is HTTP which is unencrypted websites and your computer gets this and knows it needs to be handled by a web browser.
There are several ports your router will allow to transit between the “public” internet, and your “private” network. Traffic coming to your router on port 23 (telnet) will likely be blocked as that’s an unencrypted command line interface and is a security risk. But, port 53 which is DNS will be allowed through because when you type reddit.com into your browser it doesn’t know how to contact the reddit server. So on port 53 it sends a request for an ip address for reddit.com to a DNS server, which will receive the request and respond with the ip address for the reddit web server.
Now, some ports like those used with PTP file sharing might either be blocked or when they contact your public IP address (router) the router doesn’t know where they’re supposed to go in your private network. Like sending a letter to the marketing depart of a company. You only know the street address (public IP) of the building but don’t know the office room number (local IP in private network) but it’s labeled marketing (say the port number) and because you have port forwardimg rules set up the mail room (router) knows anything with marketing goes to the marketing office room. Without the port forwarding rule its likely the mail room (router) will just drop the package in the trash and it will not go through.
Edit: this was a quick overly simplistic description to simply get the point across. I know its not perfect and the tip of the iceberg.
I see all over here that it is required to torrent files.
Port Forwarding is not required to download files in your torrent client.
However, if you like to upload files to other torrent users it usually works much better if you have port forwarding enabled.
Forwarding a port on your router (or another device with a public IP address) to your computer (without a public IP address) is a work-around that’s needed because of IPv4 address scarcity, and because some protocols aren’t that NAT friendly (for example they may perform worse with NAT, if at all).
Port forwarding is not always required. The “randomized” ports you’re talking about are called ephemeral ports. Feel free to look it up, as I said in my original comment I was simply giving a tip of the iceberg explanation.
How is it that I’ve PTP’ied with randomized port in my PTP client, without any port forwarding rule and never had issues?
Port Forwarding is not required to download files in your torrent client.
I’ve used a similar model, describing a Post Office with 65,535 P.O. Boxes. It’s not a very attractive one for junk mailers, as you can only attempt to deliver unsolicited mail to maybe one or two, or say 10 at most, PO(rt) addresses.