A secure web gateway (SWG) is a type of security solution that is designed to protect organizations from internet-based threats. It sits between an organization's network and the internet and acts as a gatekeeper, controlling access to the internet and monitoring all incoming and outgoing web traffic. 

The main function of an SWG is to filter web traffic and block malicious or unwanted content. This can include blocking access to known malicious websites, blocking downloads of certain file types, and blocking the use of certain protocols (like peer-to-peer file sharing). 

Some SWG also provide advanced features like malware protection, URL filtering, Content filtering, Advanced threat protection, Data Loss prevention (DLP) etc. 

One of the key benefits of an SWG is that it can help to prevent malicious traffic from entering an organization's network, which can help to reduce the risk of data breaches and other security incidents. It also allows organizations to set and enforce their own policies for internet use, which can help to prevent employees from accidentally accessing malicious or unwanted content. 

An SWG can be deployed as a physical appliance, virtual appliance, or cloud-based service, as per organization's requirement and IT infrastructure. It can be integrated with other security solutions like firewalls, intrusion prevention systems, and endpoint security software to provide a comprehensive security defense. 

It's important to note that, A Secure Web Gateway alone is not enough to protect an organization from all the potential internet-based threat, it should be combined with other security solutions and robust security practices to ensure a comprehensive security.