As the Internet and Digital Economy have grown up, the humble Firewall has continued to serve as their go-to security appliance. In spite of the evolution of the Firewall through a number of shapes, functions, and roles, it remains the security foundation for implementing the strategic pillars of Segmentation, Access Control, and Real-time analytics/action now and into the future. Firewalls have four distinct but related evolutionary traits, and each genus has undergone important changes since their inception.”]
Source: https://www.csoonline.com/article/3208344/the-evolution-of-the-firewall.html