Malware
Software that is there to harm you: steal, lock, spy, or hitch a ride. Virus, worm, Trojan, ransomware — different delivery, same job.
Malware is hostile software. The job is harm: theft, destruction, extra programs nobody asked for, or knocking a network over. Viruses, worms, Trojans, spyware, adware, and rootkits are species, not a complete census. The label is the intent, not the file extension.
It arrives by phishing, poisoned ads, a compromised site, a supply-chain update, or removable media nobody should have plugged in. Defence is boring and effective: patch, restrict admin, application control, mail authentication, EDR that can isolate, and users who can report without being mocked.
You do not need the strain name to respond. You need scope, containment, and whether identity was stolen on the way through.
Fact source: ASD's ACSC glossary.