The subjunctive in English is used to form sentences that do not describe known objective facts. These include statements about one's state of mind, such as opinion, belief, purpose, intention, or desire. It contrasts with the indicative mood, which is used for statements of fact, such as He speaks English.
In Modern English, the subjunctive form of a verb often looks identical to the indicative form, and thus subjunctives are not a very visible grammatical feature of English. For most verbs, the only distinct subjunctive form is found in the third person singular of the present tense, where the subjunctive lacks the -s ending: It is necessary that he see a doctor (contrasted with the indicative he sees). However, the verb be has not only a distinct present subjunctive (be, as in I suggest that he be removed) but also a past subjunctive were (as in If he were rich, …).
These two tenses of the subjunctive have no particular connection in meaning with present and past time. Terminology varies; sometimes what is called the present subjunctive here is referred to simply as the subjunctive, and the form were may be treated just as an alternative irrealis form of was rather than a past subjunctive.
Another case where present subjunctive forms are distinguished from indicatives is when they are negated: compare I recommend that they not enter the competition (subjunctive) with I hope that they do not enter the competition (indicative).
English has present subjunctive and past subjunctive forms, which are often similar to the present indicative and past indicative forms (the familiar present and past tense forms of verbs). Note that these terms are used here merely as names for forms that verbs take; the use of "present subjunctive" and "past subjunctive" forms is not limited to referring to present and past time. (Sometimes the term subjunctive is used only to refer to what is called here the present subjunctive.)
The present subjunctive is identical to the bare infinitive (and imperative) of the verb in all forms. This means that, for almost all verbs, the present subjunctive differs from the present indicative only in the third person singular form, which lacks the ending -s in the subjunctive.