"What do you mean 'system?'''
It means that our (yes plural^^) body has developed a truama based disorder called Dissociative Identity Disorder or DID, formerly known as Multiple Personality Disorder!
(Endogenic systems DNI unless your trying to be educated.)
Below are some resources for researching / understanding plurality (being a system!)
The sites below aren't STRICTLY for DID, but they talk about plurality as a whole, rather than just one form of it


Info about being plural (CLICK ME)
The link above should teach you aboutWhat Causes DID/OSDD?
How Alters/Parts are Experienced Internally
Parts In Control
Elaboration of Parts
What Is Integration?
Splits in Established Systems
Substitute Beliefs
One Person’s Experience of Having Dissociated Parts
Parts and MemoriesAnd more
Use this if you need help understanding, or if somebody has come out to you as a system.(CLICK ME)
This website tells you how to treat a family member who is plural, it tells you what alters are, and its also shows what exactly being plural IS

Thank you for visiting!
If you have any other questions regarding plurality, you can message us on discord
.the_static_company.