Fault Tolerance is the concept that even if there is some failure in the components that make the internet function, the entire system can remain stable because there backup components and systems in place.
The internet protocol is set of rules and standards that enable data to travel across the internet. The IP is a group of standards that includes IP addresses, TCP, UDP, and several other standards.
TCP is the main protocol that enables reliable data transfer across the internet. In a TCP connection, data is broken up into small packets that each contain a sequential header. In the TCP connection, the sender and receiver make sure that all packets have been received and ordered correctly. If not, missing packets are resent before the connection closes.
The word router has multiple meanings. To the end user, a router is a device that multiple computers connect to in order to access the internet.
A path is a set of wired connections that data travels upon. When data is broken up into packets, each packet can take a different path from sender to receiver. One of the concepts that makes the internet fault-tolerant is having multiple paths that connect routers so that if one path goes down, another redundant path can be used.
From Wikipedia..."Redundancy is the intentional duplication of critical components or functions of a system with the goal of increasing reliability of the system."
Fault Tolerance is the concept that even if there is some failure in the components that make the internet function, the entire system can remain stable because there backup components and systems in place.