What is a Activision account for modern warfare?

Managing Your Activision Account

How to Add Friends with Crossplay!

So I just got warzone, and I need to create an Activision account, as this is the first time it's required. I try to enter in my information, but it says invalid

How do I find my Activision ID? — CoD Mobile Help Center

How to log into an Activision Account - PC Guide

How to add friends by Activision ID in Call of Duty: Vanguard

So Activision allowed my account to be hacked, what's next? : r/modernwarfare

Error Connecting to Activision Account: 5 Ways to Fix It

How to get back stolen & hacked CoD Activision accounts - Charlie INTEL

500,000 Activision accounts have been leaked