Past

The past is the set of all spacetime that occurred before a given point in time. The past is contrasted with and defined by the present and the future. The concept of the past is derived from the linear fashion in which human observers experience time, and is accessed through memory and recollection. In addition, human beings have recorded history since the advent of written language. The first known use of the word "past" was in the fourteenth century; it developed as the past participle of the Middle English verb passen meaning "to pass." In grammar, actions are classified according to one of the following twelve verb tenses: past (past, uses of English verb forms, past perfect, or past perfect continuous), present (present, present continuous, present perfect, or present perfect continuous), or future (future, future continuous, future perfect, or future perfect continuous). The past tense refers to actions that have already happened. For example, "she is walking" refers to a girl who is currently walking (present tense), while "she walked" refers to a girl who was walking before now (past tense). The past continuous tense refers to actions that continued for a period of time, as in the sentence "she was walking," which describes an action that was still happening in a prior window of time to which a speaker is presently referring. The past perfect tense is used to describe actions that were already completed by a specific point in the past. For example, "she had walked" describes an action that took place in the past and was also completed in the past. The past perfects continuous tense refers to an action that was happening up until a particular point in the past but was completed. It is different from the past perfect tense because the emphasis of past perfect continuous verbs is not on the action having been completed by the present moment, but rather on its having taken place actively over a time period before another moment in the past.