Anti-virus software is a program or set of programs designed to detect, search for, prevent, and remove software viruses, and other malicious software like worms, trojans, adware, and more. These tools are critical for preventing and mitigating the damage caused by such threats. Anti-virus software typically performs real-time scanning in the background to detect and block the execution of malware as it occurs, periodic scans of a file system, or both. It also often includes features like heuristic analysis to identify previously unknown viruses, as well as the ability to remove or quarantine infected files. Regular updates of virus definitions are crucial for anti-virus programs to effectively protect against newly developed malware.