k-anonymity
k-anonymity is a data property where each record is indistinguishable from at least k−1 others on identifying attributes.
k-anonymity protects against re-identification: data is generalized and grouped so that, across a set of quasi-identifiers (age, department, and so on), every record matches at least k−1 others. In HR surveys and analytics this threshold lets you publish breakdowns without exposing the answers of any single employee.