When we talk about RJ45 ("Registered Jack" 45) we refer to a telecommunications network interface for wired connection of voice and data equipment.

This connector has 8 pins or connections and may have a specific category depending on the data transfer speed and bandwidth (category 5e, 6, etc.)

The common application is their use in Ethernet network cables under TIA/EIA-568-B standard that defines the arrangement of pins (pinout), but can also be used for other applications.

- Direct pin diagram:

EIA-568A
Pin No.1: WHITE-GREEN
Pin No.2: GREEN
Pin No.3: WHITE-ORANGE
Pin No.4: BLUE
Pin No.5: WHITE-BLUE
Pin No.6: ORANGE
Pin No.7: WHITE-BROWN
Pin No.8: BROWN

EIA-568B
Pin No.1: WHITE-ORANGE
Pin No.2: ORANGE
Pin No.3: WHITE-GREEN
Pin No.4: BLUE
Pin No.5: WHITE-BLUE
Pin No.6: GREEN
Pin No.7: WHITE-BROWN
Pin No.8: BROWN

- Schematic of crossed pins:

The crossover cable has one end with EIA-568A scheme and the other one with EIA-568B.

Depending on the quality and type, network cables are classified into categories that help us know the characteristics of them.

The categories of network cables most commonly used are:

- Category 5
- Category 5e
- Category 6
- Category 6
- Category 7

As can be seen, category 5e (enhanced or improved) and category 6A (Augmented), are an improvement of categories 5and 6, respectively, which it has improved the top speed and bandwidth.

The higher the category, the higher the speed of maximum data, the maximum 100 meters distance as its standard.

You can see a table which shows the 5 categories, where V is the maximum velocity, D is the maximum and MHz frequency which can work away.

CAT7 is an unshielded twisted pair (UTP) cabling standard used for local area networks (LANs). It is the latest and most advanced standard in the telecommunications industry's series of twisted pair category standards.

CAT7 has a higher data transmission rate than its predecessors, with a nominal speed of 10 Gbps (gigabits per second) in a frequency range of 600 MHz. In addition, it has a higher shielding capacity, which means that it is less prone to electromagnetic interference (EMI) and crosstalk (interference between wire pairs).

CAT7 also has a longer range of cable lengths, which means it can transmit data over a greater distance without the need for repeaters. This cabling standard is ideal for high-speed and secure network environments such as data centers, corporate computer networks, and surveillance networks. However, it is less common and more expensive than older standards like CAT5 or CAT6.