The word tense comes from the Latin word, tempus, which means "time." The tense of a verb shows the time when an action or condition occurred. In English the tense also may provide emphasis and may determine whether or not an action or condition was continuous or repetitive.
There are fourteen tenses in modern English.
There are three basic tenses: past, present, and future. They show whether a simple action or condition occurred, occurs, or will occur in the past, present, or future.
There are three perfect tenses: past perfect, present perfect, and future perfect. They show whether an action or condition had occurred relative to the past, has occurred relative to the present, or will have occurred relative to the future.
There are six progressive tenses: past progressive, present progressive, future progressive, past perfect progressive, present perfect progressive, and future perfect progressive. They show a continuous action or condition that was occurring in the past, is occurring in the present, will be occurring in the future, had been occurring relative to the past, has been occurring relative to the present, or will have been occurring relative to the future.
There are two emphatic tenses: past emphatic and present emphatic. They provide emphasis especially in questions and negatives for actions or conditions that did occur in the past or that do occur in the present.
In the above explanations the verb to occur was conjugated in each of the fourteen tenses respectively.
For more on each type of tense, see the individual entry in the glossary.
Some authorities consider verbs formed with the conditional auxiliary verbs as one or several conditional tenses to show actions that could occur, might occur, should occur, would occur, could have occurred, might have occurred, should have occurred, and would have occurred. They also can refer to something that has happened in the past after the main action (a "future past"). Other authorities consider could, might, should, and would as simply the past or perfect forms of the verbs can, may, shall, and will.
Conditional: I wish she would answer me.
Past Tense: Little did he realize that in twenty years he would be president.