Spyware
Software that watches what you do without a real yes. Sometimes bundled. Sometimes smuggled.
Spyware records a user's activity without informed consent: browsing, credentials, documents. It can arrive as a sneaky extra in otherwise 'real' software, or as a straight hostile implant.
Treat unexpected new toolbars, 'optimisers', and monitoring agents you did not procure as incidents. EDR, least privilege, and a software allow-list cut the easy installs.
Fact source: ASD's ACSC glossary.