Totalitarianism is any political system, or ideologies that support such a system, in which a centralized political authority controls every aspects of life, including economics, culture, and religion, and all civil institutions are tightly under the direct authority of the government. Political oppression, show trials and summary executions are generally prevalent in totalitarian states. Civil liberties are little or non-existent in totalitarian societies. The government in a totalitarian society often uses police and intelligence organizations to enforce its power and to terrorize the populace, often with powers of extrajudicial detention.
"Police state" implies that the control mechanism is the dominant aspect of government. The Soviet Union, for example, had, as a major part of its government, the Organs of State Security. Nazi Germany had a complex Reich Main Security Administration. More recently, Iraq, before the Gulf War, was dominated by the security organization of Saddam Hussein.
There are many analytic works on the origin and structure of totalitarianism. One of the most famous one is Origins of Totalitarianism, a tome authored by German philosopher Hannah Arendt. Francis Fukuyama discusses the need for control in The End of History and the Last Man.