Data breach
Also known as: confidentiality incident · privacy breach · data leak
A data breach is any access, use, disclosure or loss of personal information not authorised by law.
The idea is broader than hacking. An email sent to the wrong recipient, a lost laptop, a trash folder not emptied before a machine is resold, or a database made public by a misconfiguration are all breaches.
The duty to report turns on a severity test — serious risk, or significant harm, depending on the regime — and the deadlines are short, counted in hours or days from becoming aware.
Several regimes additionally require keeping a record of every breach, including those below the reporting threshold.
What it means for a small business
The obstacle in practice is not legal, it is organisational: without a written procedure, nobody knows who decides to report, or when the clock started.
Related terms
So what actually applies to you?
A definition tells you what a term means, not what your organization must do. The assessment answers the second question — free, no credit card.
Updated September 1, 2026 · Educational definition; not legal advice.