Do you pass this sentence? "The number of ports a hub refers to is the number of RJ-45 ports it has." So, what is a hub?
What is a hub?
"Hub" means "center".
The primary role of the hub is to rejuvenate, mold, and boost the signal it receives. This is done to extend the network's transmission range. All nodes simultaneously focus on the node that is at their center.
It works on the first layer of the OSI reference model, the "physical layer". Hubs, like network cards, network cables and other transmission media, are basic devices in the local area network.
Implement the CSMA/CD method for media access control. Every hub interface merely transmits and accepts bits. If it receives a 1, it will forward a 1. If it receives a 0, it forwards a 0 without performing collision detection.

Hubs are pure hardware network bottom equipment. It also doesn't have the MAC address table that a switch has. So when it sends data, it is not targeted.
Instead, it is sent by broadcast. When it wants to send data to a specific node, it doesn't send the data directly to that node. Instead, the packet is sent to all nodes connected to the hub.
HUB is a multi-port repeater. When the HUB is used as the central device, a fault occurs on a certain line in the network. This does not affect the work of other lines.
Most of the time it is used in star and tree network topologies and is connected to each host through an RJ45 interface.
A hub is a device that connects many Ethernet cables or optical fibers together using the same physical medium. A hub functions at the physical layer of the OSI model. It can be viewed as a repeater with multiple ports. Upon detecting a collision, it sends out a blocking signal.
Hubs usually come with BNC and/or AUI adapters to connect to traditional 10BASE2 or 10BASE5 networks.
The above is an introduction to the hub. I hope you who are reading this article will have a better understanding of hubs.