Understanding the nginx proxy_cache_path directive

What does the keys_zone=myCache:8m mean? As documentation said, nginx will keep all active keys and information about data are stored in a shared memory zone, whose name and size are configured by the keys_zone parameter. As a matter of completeness, lets break down per part /var/cache/nginx is the place where the actual cache stored. Inside the folder, cache file was binary file but you can easil