Routers carry out two basic functions—they select a path between networks, and they securely transmit information packets across that path toward an intended destination.

A router is a networking device that is primarily used for connecting multiple devices to a single Internet connection. It acts as a central hub that allows different devices, such as computers, smartphones, tablets, and gaming consoles, to access the internet simultaneously. The router receives and forwards data packets between the devices and the internet, ensuring that the data is sent to the correct destination.

Let's delve into the details of why a router is used:

1. Connecting Multiple Devices:
- One of the main functions of a router is to create a local area network (LAN) that enables multiple devices to connect to a single internet connection.
- By using wired or wireless connections, a router allows devices within its network to communicate with each other and access the internet simultaneously.

2. Network Address Translation (NAT):
- A router uses Network Address Translation (NAT) to assign private IP addresses to devices within its network.
- This means that all devices connected to the router will have a unique private IP address, while the router itself will have a public IP address that is visible on the internet.
- NAT helps in conserving IP addresses and provides an extra layer of security by hiding the private IP addresses from external networks.

3. Firewall and Security:
- Many routers include built-in firewall features that help protect the network from unauthorized access and potential threats.
- Routers can block certain incoming connections, filter packets based on predefined rules, and provide other security measures to safeguard the network and its connected devices.
- However, it is important to note that while routers provide some level of security, additional security measures, such as antivirus software and strong passwords, are still necessary to ensure complete protection.

4. Wireless Access Point:
- Most modern routers also include a wireless access point, allowing devices to connect to the network wirelessly using Wi-Fi.
- This enables devices like laptops, smartphones, and tablets to access the internet without the need for physical connections.
- The router acts as a bridge between the wired and wireless devices, ensuring seamless communication between them.

5. Quality of Service (QoS):
- Routers often have Quality of Service (QoS) capabilities, which allow for prioritization of network traffic.
- This means certain types of data, such as video streaming or online gaming, can be given higher priority over other less time-sensitive data, ensuring a smoother and uninterrupted experience for users.

In conclusion, a router is primarily used to connect multiple devices to a single internet connection, allowing them to communicate with each other and access the internet simultaneously. It provides network address translation, firewall security, wireless access, and quality of service features, making it an essential component in modern networking setups.