Disk cleaners, antivirus software, backup software, and compression software are all classified as utility software.

Explanation

• Utility software is a type of system software designed to help manage, maintain, and optimize computer resources and system performance.
• Disk cleaners assist in removing unnecessary files to free up space.
• Antivirus software protects the system from malware and security threats.
• Backup software allows users to create copies of important data to restore in case of data loss.
• Compression software reduces file sizes to save storage space and facilitate data transfer.

This category of software is distinct from application software, as it primarily focuses on system maintenance rather than user-oriented tasks.