Classified information is material that a government body claims is sensitive information that requires protection of confidentiality, integrity, or availability. Access is restricted by law or regulation to particular groups of people, and mishandling can incur criminal penalties and loss of respect. A formal security clearance is often required to handle classified documents or access classified data. The clearance process usually requires a satisfactory background investigation. Documents and other information assets are typically marked with one of several (hierarchical) levels of sensitivity—e.g. restricted, confidential, secret and top secret. The choice of level is often based on an impact assessment; governments often have their own set of rules which include the levels, rules on determining the level for an information asset, and rules on how to protect information classified at each level. This often includes security clearances for personnel handling the information. Although "classified information" refers to the formal categorization and marking of material by level of sensitivity, it has also developed a sense synonymous with "censored" in US English. A distinction is often made between formal security classification and privacy markings such as "commercial in confidence". Classifications can be used with additional keywords that give more detailed instructions on how data should be used or protected.