Under certain circumstances, information is only as good as the security measures used to protect it. Sometimes the best way to protect sensitive information or a proprietary secret is to limit the number of people who can actually possess it. This is why a number of companies or agencies deliberately dispense sensitive ideas on a strict need to know basis. Only those individuals who have legitimate reasons to access that information would be allowed to receive it.
Information held on a need to know basis is often divided among several individuals or departments so that no one individual can possess it all. When authorized engravers work on a new set of printing plates to produce government currency, for instance, each engraver only receives a section of the finished design. In this way, no single engraver ever sees the entire printing plate, so he or she could not be coerced into reproducing it for counterfeiters. Every department along the way would also be given specific information only as they need to know it.
Military intelligence and other sensitive information is often classified according to its accessibility level. A surprising number of government employees or private contractors may have access to "top secret" information, but very few would have access to ultra-secret information classified as "penumbra" or "canoe." At every level of security, there are those who need to know and those who would simply be interested in knowing.
The main purpose of a strict need to know basis is to protect the integrity of a sensitive or secret piece of information. If a suspect in a local crime happened to be participating in an undercover sting operation, for example, the federal agency in charge of the operation is not always obligated to share that information. Only those with proper credential and security clearances could possibly access this classified information.
Over the years, journalists and concerned private citizens have filed legal action in order to gain access to information the government considers to be on a need to know basis. The Freedom of Information Act (FOIA) does allow private citizens to petition government agencies for the release of declassified or public documents, but many of these documents arrive in redacted form, meaning the writing itself (or parts of it) has been covered over with black ink. Information that may affect matters of national security or ongoing criminal investigations, for example, can still be held as classified, even if the document itself is released through the Freedom of Information Act.