What wire does the RJ45 connector connect to?

author: MagTop
An RJ45 connector is commonly known as a crystal connector. 
The transparent plug that connects the network card or HUB to connect both ends of the twisted-pair cable.
RJ-45 is a network interface specification, similar to RJ-11, which is the "telephone interface" used to connect telephone lines. 
It is called "crystal head", because its appearance crystal clear.
The RJ-45 plug must be installed on both ends of the twisted-pair cable so that it can be inserted into the RJ-45 port of a NIC, Hub, or Switch
for network communication.