Tenable Nessus is a widely used vulnerability scanning and assessment tool designed to help organizations identify and address security vulnerabilities and compliance issues in their IT infrastructure. Nessus comes in several editions, with Nessus Professional being one of the most popular options for small to medium-sized businesses and individual security professionals.

Key features of Nessus Professional software include:

1. Vulnerability Scanning: Nessus scans networks, systems, and applications to identify vulnerabilities, misconfigurations, and security weaknesses. It covers a wide range of platforms and technologies.

2. Compliance Checks: Nessus can perform compliance checks against various industry standards and regulations, such as PCI DSS, HIPAA, and CIS benchmarks, to ensure that your systems meet specific security and compliance requirements.

3. Customizable Scanning: Users can customize scans by specifying targets, scanning parameters, and policies to focus on specific areas of concern or compliance requirements.

4. Credential-Based Scanning: Nessus supports authenticated scanning, allowing it to perform deeper assessments by logging into systems and applications with valid credentials to identify vulnerabilities that might not be visible externally.

5. Reporting: The tool generates detailed reports that provide information on identified vulnerabilities, their severity, and recommended remediation steps. Reports can be customized and scheduled for regular assessments.

6. Integration: Nessus can integrate with other security tools and platforms, such as Security Information and Event Management (SIEM) systems and ticketing systems, to streamline vulnerability management and response processes.

7. Asset Discovery: It can help organizations discover and inventory all devices on their network, providing a comprehensive view of the attack surface.

8. Plugin Support: Nessus uses a plugin-based architecture, which allows users to download and update plugins to ensure the scanner is up-to-date with the latest vulnerabilities and checks.

9. Prioritization: The tool helps users prioritize vulnerabilities by assigning severity scores and providing information on the potential impact of each vulnerability.

10. Remediation Guidance: Nessus offers guidance on how to remediate identified vulnerabilities, helping organizations take proactive steps to improve their security posture.

Nessus is widely used by security professionals, IT administrators, and organizations of all sizes to proactively identify and address security vulnerabilities, reducing the risk of cyberattacks and data breaches. It's important to note that Nessus Professional is a commercial product, and licensing fees apply based on the number of IP addresses or assets you intend to scan.