Explanation
Sandboxing involves the segregation and isolation of information or processes from other information or processes within the same system or application, typically for security concerns. Sandboxing is generally used for data isolation (for example, keeping different communities and populations of users isolated from others with similar data). In IT terminology, pooling typically means bringing together and consolidating resources or services, not segregating or separating them. Cell blocking and fencing are both erroneous terms.

Masking involves replacing specific data within a data set with new values. For example, with credit card fields, as most who have ever purchased anything online can attest, nearly the entire credit card number is masked with a character such as an asterisk, with the last four digits left visible for identification and confirmation.

Explanation
The United States has a myriad of regulations focused on specific types of data, such as healthcare and financial, but lacks an overall comprehensive privacy law on the national level. The European Union, the Asian-Pacific Economic Cooperation, and Russia all have national privacy protections and regulations for the handling the PII data of their citizens.