Which Internet appliance is used to spread incoming traffic over many resources, such as web servers?

Load balancers do exactly what their name implies. Rather of directing all incoming traffic to a single server or device, traffic is distributed among devices. Proxy servers monitor and filter incoming and outgoing packets depending on predefined criteria. Spam gateways do not enable spam to enter; rather, they filter it out. Unified threat management (UTM) can use an appliance, software, or even an outside service to monitor and manage malicious network activity.