Trying to understand how domains work in AS3

So, in the last few days I had to deal with something like:

• allowSecurityDomain
• contentLoaderInfo
• Appdomain
• securitySandbox
• etc.

"It seems" as if these things belong to the same bag.

So, is there a tutorial / guide / guide to fully understand how these things work with security? My application is working now, but I have this "emptiness" in my omen, which shouts: "Yes, of course it works, but you didn’t understand anything. LOL."

thank:)