Every device on a network has a unique , like a mailing address for data. When you send data across the Internet, it does not go directly to its destination. Instead, it hops through that read the destination IP address and forward the data closer to where it needs to go.
This system works because of the , a shared set of rules that all devices follow. Without a common , devices would not be able to understand each other.
Imagine sending a letter across the country. You drop it in a mailbox. The post office reads the address, sends it to a regional sorting center, then to another, and finally to the destination. Each "hop" is like a router forwarding your data.
Real networks have : multiple paths between devices. This makes the network . If one router fails, data can take a different route.