Why classify
Not all information needs the same protection. Classification lets a company focus its strongest controls on what matters most, such as customer data, financial information, source code or contracts, and gives employees a simple rule for how to treat what they handle.
A typical scheme
Most companies use three or four levels. Public: can be shared freely. Internal: for employees, with low impact if leaked. Confidential: limited to those who need it, with real damage if disclosed. Restricted: the most sensitive data, with strict access, encryption and logging. Each level comes with handling rules: who can access it, where it can be stored, whether it can be sent outside the company, and how it is destroyed.
Making it work in practice
Keep the scheme simple, assign an owner to each information asset in the asset inventory, use labels in documents and email where tools allow it, and connect classification to technical controls such as DLP, access rights and backup policies. A scheme nobody uses is worse than none, because it gives a false sense of control.
Where it shows up in compliance
ISO 27001 requires information to be classified and labelled according to the organisation's needs (Annex A 5.12 and 5.13). The ENS requires information to be rated according to its security requirements, and the GDPR treats special categories of personal data as needing extra protection.
