# Network Devices ### Network A **computer network** is a digital telecommunications network which allows nodes to share resources. Nodes are as follows:

Two nodes connected together make a network, so if two PCs are connected, for example, it is already a network. ### Client and Server A client is a device which accesses a service made available by a server. E.g. smartphone, laptop, PC, tablet, etc. A server is a device which provides a service for clients. Servers are the same devices as clients but what makes them different is their functionality.

Here, both devices are PCs, so it is a **network**. However, not both are clients. Since PC1 is requesting information, it is a **client**, and PC2 is providing it, which makes PC2 a **server**. So, a client device can be a server as well. Besides that, the same device can be a client in some situations, and a server in other situations. ### Switches and Routers A local area network (**LAN)** is a collection of devices connected together in one physical location, such as a building, office, or home. A switch is a device which provides this connectivity in the LAN, not over the internet. Switches have many network interfaces/ports for end hosts to be able to connect(usually 24+). Here are some examples of switches:

A router is a device which provides connectivity between LANs and is used to send data over the internet. Routers have fewer ports than switches. Some examples of routers:

### Firewall A **firewall** is a device which monitors and controls traffic based on configured rules. It can be placed inside the network and/or outside the network. These firewalls are network-based hardware devices. But there are host-based firewalls as well. Host-based firewalls are software applications installed in the system. They usually come pre-installed with OS (Operating System). Some firewalls may include more modern and advanced capabilities. Those are called "Next-Generation Firewalls".

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