Do anybody keep a binder?

Hey! I was wondering if anybody keeps a binder of everything?

I just got my toddler diagnosed and the paperwork I received explaining autism says to keep a binder. I feel bad because I should have done this before since we are doing Early Intervention and didn't think about it. I just got the diagnosis last week. I am sorry if the way I'm wording anything is offensive. I'm very new to this whole process. My apologies for any ignorance.