According to RFC1918, there are specific IP address ranges that are reserved for private use and are not routable on the public internet. These ranges are intended for use within private networks, such as a company's intranet, and include 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16. These private address ranges are not recognized on the public internet, making them ideal for internal networking requirements. Choosing an IP address outside of these ranges for private network use could lead to conflicts with public IP addresses and is not recommended because it could potentially expose the network to routing issues or IP conflicts.