Why does my address bar show idmsa.apple.com when I’m logging into discussions?

Just out of curiosity, when I’m signing into Apple on my iPhone 8+ using my fingerprint, it shows in the address that I’m being directed to as “idmsa.Apple.com” instead of where I was prior to having to sign in which was “discussions.apple.com”.

this may be a silly question to ask but you would need to know further info to understand my concern that I may have malware or someone is remotely using my phone “aka” hacked. That’s because my phone has been hacked along with all of my other devices since they’re linked under my Apple ID. That’s a completely different topic I won’t get further into just wondering what this address is exactly.

im not a tech wiz whatsoever, so if anyone would kindly explain this address along with the multiple addresses that will flash before I’m on the page I need to be when I’m on other sites but also on different links within the Apple site. When I look at the Data Analytics or under Website Data, there are several unknown pages it shows my phone has visited. I’ve tried looking them up manually on safari but a lot of them seem to be sites that either don’t exist or I don’t have the authority to access for one reason or another. Just seems suspicious to me abd woukd like to learn about them in detail. So, again, please kindly explain in detail tge what, why, how, and maybe even who and where of address such as this one. Hackers? Malware? Spyware? Thanks!