What is a cryptocurrency unit?

Could you please elaborate on what constitutes a cryptocurrency unit? In the realm of digital finance, the term 'cryptocurrency' is often heard but its fundamental components remain somewhat mystifying. I'm curious to know if a cryptocurrency unit represents a digital token that functions as a medium of exchange, secured through cryptography and operating independently of a central bank or government. Additionally, I'm wondering if these units are divisible into smaller fractions, similar to traditional currencies, and if they have inherent value based on scarcity, demand, or some other economic factor. Clarifying these aspects would greatly assist in my understanding of cryptocurrencies.