The present tense (abbreviated PRES or PRS) is a grammatical tense whose principal function is to locate a situation or event in present time. The term present tense is usually used in descriptions of specific languages to refer to a particular grammatical form or set of forms; these may have a variety of uses, not all of which will necessarily refer to present time. For example, in the English sentence "My train leaves tomorrow morning", the verb form leaves is said to be in the present tense, even though in this particular context it refers to an event in future time. Similarly, in the historical present, the present tense is used to narrate events that occurred in the past.
There are two common types of present tense form in most Indo-European languages: the present indicative (the combination of present tense and indicative mood) and the present subjunctive (the combination of present tense and subjunctive mood).
The present indicative of most verbs in modern English has the same form as the infinitive, except for the third-person singular form, which takes the ending -[e]s. The verb be has the forms am, is, are. For details see English verbs. For the present subjunctive, see English subjunctive.
A number of multi-word constructions exist to express combinations of present tense with aspect. The basic form of the present tense is called the simple present; there are also constructions known as the present progressive (or present continuous) (e.g. am writing), the present perfect (e.g. have written), and the present perfect progressive (e.g. have been writing).