Questions about RAM usage/cache

[Psychobells]

My system has 8 GB of DDR4 RAM, which is the minimum required.  I did just order some more to get up to 16 GB, but in the meantime, I'm curious about the RAM usage.  My system right now is at 31.3% in use and 58.1% cache, leaving just a little bit extra overhead.  Is this cache usage normal or high?  How does the cache work exactly/what does it do?  Hopefully these aren't silly questions!

[Mobius]

they aren't silly questions
high ram usage is expected and normal
Ram also known as arc is used for a read cache and a tiny write cache.

for read cache it takes your most frequently accessed files and keeps a copy on the ram so next time you need it you can access it faster.

[acedog5]

I assume the cache will auto shrink if more ram usage is needed. Currently my cache is at 87% with 32GB of ram.