Network Security Appliances are hardware or software devices that protect your business from cybersecurity threats. Some different types of appliances include:

• Firewalls – Firewalls put a shield between your company’s network and the internet as a whole, blocking suspicious connections. More specifically, you might use a Web Application Firewall to protect your website and organization as a whole from any vulnerabilities within your website by monitoring HTTP traffic.
• Network Access Control – Controlling access to your company’s network is key to preventing malicious or unsecure devices from harming your system. Suspicious devices can be ‘quarantined’ to protect the rest of your network from getting infected.
• Unified Threat Management – UTMs combine multiple cybersecurity features such as firewalls and intrusion prevention and detection systems to efficiently protect your organization.
• Virtual Private Network – VPNs allow users to virtually be somewhere they’re not. For example, your employee might use a VPN to securely connect to your office network on a day they work from home. 

These are just a small portion of all the possible network security appliances available. Any application or device you use likely has a way it can be exploited by cybercriminals, and a way it can be secured with a security device.