Hytale Memories explained
One of Hytale's primary progression systems, at least as it stands in early access, are Memories. This is effectively a bestiary, taking note of every mob you stumble across as you explore, whether they're a peaceful farm animal or a disgusting floating eyeball.
However, you won't have access to Memories immediately. You've no doubt seen the prompt in the inventory screen to 'find the Forgotten Temple'—yeah, that's for the Memories. Since it's a progression system based on exploration, I recommend you unlock it as soon as you can...