What is the crystal head connection method for network cables? What are the types of network cable crystal heads?

The network cable crystal head connection method is a way of connecting network cables, commonly used for Ethernet or other local area network (LAN) connections. A crystal head is a plug used to connect network cables to network interfaces of network devices such as computers, routers, switches, etc.
The connection method of crystal heads usually follows the following standards, known as the TIA/EIA-568 specification:
T568A connection: Use pairing wires of orange/white orange, green/white green, blue/white blue, brown/white brown to connect. Among them, the white line corresponds to the bottom of the solid color line.
T568B connection: Use pairing wires of orange/white orange, green/white green, blue/white blue, brown/white brown to connect. Among them, the white line corresponds to the top of the solid color line.
These two connection methods have slight differences in the order of pairing lines, but both can transmit data normally. In practical applications, the T568B connection is more common, especially in North America.
As for the types of network cable crystal heads, there are mainly the following:
RJ-45 crystal head: The most common network cable crystal head used to connect CAT5, CAT5e, CAT6, CAT6a and other network cables. It has 8 metal contact points for transmitting signals and currents from 8 paired wires.
RJ-11 crystal head: commonly used for telephone line connection, smaller than RJ-45 crystal head, with only 6 metal contact points.
RJ-12 crystal head: Similar to RJ-11, but with 6 or more metal contact points, typically used to connect multi line telephone systems.
RJ-48 crystal head: used for T1 (digital transmission 1) lines, similar to RJ-45, but with a different pin layout.
These types of crystal heads are mainly classified based on their design purposes and differences in pin configurations. In the network, RJ-45 crystal head is the most common and widely used type.