What is an internet subnet mask?

I noticed it when I was looking at my computer's IP address and connection status but I don't know what it is. Does it change as well?What is an internet subnet mask?
A subnetwork, or subnet, is a portion of the network's computers and network devices that have a common, designated IP address routing prefix.


A subnet allows the flow of network traffic between hosts to be segregated based on a network configuration. By organizing hosts into logical groups, subnetting can improve network security and performance.


Subnetting enables the network administrator to further divide the host part of the address into two or more subnets.


Like IP addresses, a subnet mask contains four bytes (32 bits) and is often written using the same ';dotted-decimal'; notation. For example, a very common subnet mask in its binary representation





11111111 11111111 11111111 00000000





is typically shown in the equivalent, more readable form





255.255.255.0





A subnet mask neither works like an IP address, nor does it exist independently from them. Instead, subnet masks accompany an IP address and the two values work together. Applying the subnet mask to an IP address splits the address into two parts, an ';extended network address'; and a host address. What is an internet subnet mask?
It does not change on your computer. The short, non-technical answer is the subnet mask lets your computer know which other computers it can connect to on the local network.