Censorship is the suppression of speech or deletion of communicative material which may be considered objectionable, harmful or sensitive, as determined by a censor. The rationale for censorship is different for various types of data censored:

• Moral censorship is the removal of materials that censor deems to be obscene or otherwise morally questionable. Pornography, for example, is often censored under this rationale, especially child pornography, which is censored in most jurisdictions in the world. In another example, graphic violence resulted in the censorship of the "culturally, historically, or aesthetically significant" movie entitled Scarface, originally completed in 1932.
• Military censorship is the process of keeping military intelligence and tactics confidential and away from the enemy. This is used to counter espionage, which is the process of gleaning military information. Very often, militaries will also attempt to suppress politically inconvenient information even if those information has no actual intelligence value.
• Political censorship occurs when governments hold back secret information from their citizens. The logic is to prevent the free expression needed to rebel. Any dissent against the government is thought to be a "weakness" for the enemy to exploit.Fact: date=September 2007 Campaign tactics are also often kept secret: see the Watergate scandal.
• Religious censorship is the means by which any material objectionable to a certain faith is removed. This often involves a dominant religion forcing limitations on less prevalent ones. Alternatively, one religion may shun the works of another when they believe the content is not appropriate for their faith.
• Corporate censorship is the process by which editors in corporate media outlets intervene to halt the publishing of information that portrays their business or business partners in a negative light. Privately owned corporations in the business of reporting the news also sometimes refuse to distribute information due to the potential loss of advertiser revenue or shareholder value which adverse publicity may bring. See media bias. Trade secret law may be used by corporations as a censorship device. For example, trade secret law may help keep company-sponsored research confidential, when revealing it would reveal negative health effects of the product researched.

Censorship of state secrets and prevention of attention

. Typically it involves keeping times or locations secret, or delaying the release of information (e.g., an operational objective) until it is of no possible use to enemy forces. The moral issues here are often seen as somewhat different, as release of tactical information usually presents a greater risk of casualties among one's own forces and could possibly lead to loss of the overall conflict.