system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: I read once that deja vue is caused by a mistake in creating memories, but how does that work. How does your brain decide what to remember and what not remember?

Sorry if it’s a little long. Most of my deja vue moments seem to be moments that would be insignificant and I can’t remember any deja vue moments when I try to, so why would my brain want to store it as such?
gpt
Like computers, you have 2 kinds of memories:  RAM and SSD. Ram is instantly accessed and modified and that's what you use to live throughout your day without randomly dropping things because you forgot you were holding them or being able to remember a small series of numbers for a few minutes until they become obsolete. If the information regularly comes back or if it never becomes obsolete, you mind understands that it should be something important and thus transfers it in your long term memory (the SSD). For those reasons, Instant memory (RAM) is linked to present events while long term memory (SSD) is rather linked to past events.
Déjà-vu is just your brain mistakenly placing a new information directly in your long term memory. The situation feels familiar because you have instantly created a memory of it, which usually takes time. Also, this kind of memory is usually linked to past events so you get the feeling of the situation being tied to the past  .