system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do the first 4 numbers of my IPV6 Address never change?

Ive noticed lately that the first 4 numbers of my ipv6 address never change. For example my ip address looks like this xxxx:xx:xxxx:xxxx:fd50:56d4:8e2d:c6c4 

Where the x's remain constant and the last 4 numbers change constantly. What do those first 4 numbers mean and why dont they change?
gpt
The first 64 bits of your ip address is your network. It is assigned or given to you by your provider. Just like your house number never changes (without a lot of extra planning) your network won't change (without a lot of extra planning). 

The last 64 bits are your device address. Depending on your network configuration and type of device, it may change frequently, or may not change at all. A server's IP is likely to be static, and a desktop, phone, or refrigerator will have a temporary IP so someone can't use your IP to scan or hack your device.