Antivirus software is a foundational endpoint security solution installed directly on end-user devices (endpoints) such as desktops, laptops, and servers. Its primary purpose is to scan, detect, prevent, and remove malicious software (malware), including viruses, worms, and trojans. While modern security has evolved into Endpoint Protection Platforms (EPP) and Endpoint Detection and Response (EDR), traditional antivirus remains a core, commonly recognized component of endpoint security.

A. Encryption: Encryption is a process for protecting data confidentiality at rest or in transit, not a solution that actively detects or prevents threats like malware on an endpoint.

B. Intrusion Detection System (IDS): An IDS is predominantly a network security solution that monitors network traffic for malicious activity, rather than a security tool installed on individual endpoints.

C. Firewall: A firewall is primarily a network security device that filters traffic between networks. While host-based firewalls exist on endpoints, antivirus is more specific to endpoint threat protection.

1. Official Vendor Documentation: Cisco, "Cisco Secure Endpoint Data Sheet." The document describes the solution's core function: "Cisco Secure Endpoint... offers a cloud-native solution that provides advanced malware protection for endpoints." This establishes anti-malware (the modern term for antivirus) as a primary endpoint solution. (Reference: Cisco Secure Endpoint Data Sheet, Page 1, "Product overview").

2. Peer-reviewed Academic Publications: Santos, O., & Stuppi, J. (2011). CCNA Security 640-554 Official Cert Guide. Cisco Press. Chapter 2, "Network and Information Security Overview," section "Host-Based Security," explicitly lists "Antivirus software" as a key example of a security measure deployed on an endpoint or host. (Reference: Chapter 2, Page 38).

3. University Courseware: Saltzer, J. H., & Kaashoek, M. F. (2009). Principles of Computer System Design: An Introduction. MIT OpenCourseWare. Chapter 11, "Security and Protection," discusses host-based security mechanisms. Section 11.5.2, "Malicious Code," details the role of virus scanners (antivirus) as a primary defense on end-user machines. (Reference: Chapter 11, Section 11.5.2).