Insider threat
Risk originating from someone who already has legitimate access: an employee, contractor, or partner.
Most insider incidents are not malicious. They are a departing salesperson copying their contact list, a well-meaning employee moving files to personal storage to work at home, or an admin taking a shortcut. The damage is real regardless of intent.
Controls that help are the same ones that limit external attackers: least privilege, monitoring of unusual data movement, and a genuinely enforced offboarding process that removes access on the day someone leaves.
Where this comes up
Insider threat sits inside our cybersecurity and threats work. If you are trying to work out what this means for your own environment rather than in the abstract, that is the page worth reading next, and a short call will get you a straight answer faster than either.