* Verb: This is the most common usage. It means to assign something to a particular category or group.
* Example: "The documents were classified as top secret."
* Adjective: This form describes something that has been assigned to a specific category or group.
* Example: "The classified information was leaked to the press."
* Past Participle: This is a form of the verb that can be used as an adjective or part of a verb phrase.
* Example: "The information has been classified for decades."
It's important to look at the sentence to determine the intended meaning and part of speech.