How do I keep my pictures on iCloud….

How do I keep my pictures and stuff in iCloud but free space on my phone????

i don’t quite understand how this works. I’ve been paying for the largest amount of iCloud space and still… it’s almost empty and my phone is full to the brim it barely works.

if I free space in my phone I get messages that it’s also deleted from iCloud. 🤷🏽‍♀️

so what’s the purpose of iCloud anyways??????