The subjunctive mood, sometimes called conjunctive mood, has several uses in dependent clauses. Examples include discussing hypothetical or unlikely events, expressing opinions or emotions, or making polite requests (the exact scope is language-specific). A subjunctive mood exists in English, but native English speakers need not use it. Example: "I suggested that Paul eat an apple", Paul is not in fact eating an apple. Contrast this with the sentence "Paul eats an apple", where the verb "to eat" is in the present tense, indicative mood. Another way, especially in British English, of expressing this might be "I suggested that Paul should eat an apple", derived from "Paul should eat an apple."
Other uses of the subjunctive in English, as in "And if he be not able to bring a lamb, then he shall bring for his trespass..." (KJV Leviticus 5:7) have definitely become archaic. Statements such as "I will ensure that he leave immediately" often sound archaic or overly formal, and have been almost completely supplanted by constructions with the indicative, like "I will ensure that he leaves immediately".
The subjunctive mood figures prominently in the grammar of Persian and the Romance languages, which require this mood for certain types of dependent clauses. This point commonly causes difficulty for English speakers learning these languages.
In certain other languages, the dubitative or the conditional moods may be employed instead of the subjunctive in referring to doubtful or unlikely events (see the main article).
Eg: 'If I love you.'
The dubitative mood is used in Ojibwe, Turkish, and other languages. It expresses the speaker's doubt or uncertainty about the event denoted by the verb. For example, in Ojibwe, Baawitigong igo ayaa noongom translates as "he is in California today." When the dubitative suffix -dog is added, this becomes Baawitigong igo ayaadog noongom, "I guess he must be in California.
Eg: 'I could love you [if...]'
The potential mood (abbreviated pot) is a mood of probability indicating that, in the opinion of the speaker, the action or occurrence is considered likely. It is used in Persian, Finnish, Japanese, in Sanskrit and in the Sámi languages. (In Japanese it is often called something like tentative, since potential is used to refer to a voice indicating capability to perform the action.)
In Finnish, it is mostly a literary device, as it has virtually disappeared from daily spoken language in most dialects. Its suffix is -ne-, as in *men + ne + e → mennee "(s/he/it) will probably go". Some kinds of consonant clusters simplify to geminates. This simplification occurs progressively (*rne → rre) with the resonant consonants L, R, and S, and regressively with stops (*tne → nne) and is meant to prevent the violation of phonotactical rules concerning sonority hierarchy. For example, korjata → *korjat + ne + t → korjannet "you will probably fix", or tulla → *tul + ne + e → tullee "s/he/it will probably come". The potential mood can be used only in present and perfect tenses. The verb ole- "be" is replaced by lie, so that "(it) is probably" is lienee (not *ollee). Thus, in the perfect tense, which is formed with an auxiliary verb, the auxiliary verb lie is used instead of ole- as liene-, e.g. lienet korjannut "you have probably fixed" (not *ollet korjannut). In spoken language, the word kai "probably" is used instead, e.g. se kai tulee "he probably comes", instead of hän tullee.
The presumptive mood is used in Romanian to express presupposition or hypothesis regarding the fact denoted by the verb, as well as other more or less similar attitudes: doubt, curiosity, concern, condition, indifference, inevitability. For example, acolo s-o fi dus "he might have gone there" shows the basic presupposition use, while the following excerpt from a poem of Eminescu
shows the use both in a conditional clause de-o fi "suppose it is" and in a main clause showing an attitude of submission to fate le-om duce "we would bear".
Eg: There is no exact English example, although it could be translated as: '[Even] If I loved you [...]'
The conditional mood (abbreviated cond) is used to speak of an event whose realization is dependent upon another condition, particularly, but not exclusively, in conditional sentences. In Modern English, it is a periphrastic construction, with the form would + infinitive, e.g. I would buy. In other languages, such as Spanish, French or Sanskrit verbs have a specific conditional inflection. This applies also to some verbs in German, in which the conditional mood is conventially called Konjuntiv II, differing from Konjunktiv I. Thus, the conditional version of "John eats if he is hungry" is:
Johannes würde essen, wenn er Hunger hätte is also acceptable in German
In the Romance languages, the conditional form is used primarily in the apodosis (main clause) of conditional clauses, and in a few set phrases where it expresses courtesy or doubt. The main verb in the protasis (dependent clause) is either in the subjunctive or in the indicative mood. However, this is not a universal trait: among others in German (as above) and in Finnish the conditional mood is used in both the apodosis and the protasis. A further example is the sentence "I would buy a house if I earned a lot of money", where in Finnish both clauses have the conditional marker -isi-: Ostaisin talon, jos ansaitsisin paljon rahaa. In Polish the conditional marker -by also appears twice: Kupiłbym dom, gdybym zarabiał dużo pieniędzy. Because English is used as a lingua franca, a similar kind of doubling of the word would is a fairly common way to misuse an English language construction.
In English, too, the would + infinitive construct can be employed in main clauses, with a subjunctive sense: "If you would only tell me what is troubling you, I might be able to help".
Eg: 'I would love you'
In Sanskrit, the conditional is formed from the future stem as in the Romance languages. The augment of the indicative imperfact is prefixed and the endings of the latter tense are added, e.g. adaasyat "he would give" (daasyati "he will give"). The conditional, however, is rarely used and is somewhat artificial. Generally, the optative is used instead.
The optative mood expresses hopes, wishes or commands and has other uses that may overlap with the subjunctive mood. Few languages have an optative as a distinct mood; some that do are Albanian, Ancient Greek, Sanskrit, Finnish, and all forms of the Persian language (Avestan, Old Persian, Middle Persian, New Persian).
In Finnish, the mood may be called an "archaic" or "formal imperative", even if it has other uses; nevertheless, it does express formality at least. For example, the ninth Article of the Universal Declaration of Human Rights begins with Älköön ketään pidätettäkö mielivaltaisesti, "Not anyone shall be arrested arbitrarily", where älköön pidätettäkö "shall not be arrested" is the optative of ei pidätetä "is not arrested". (Also, using the conditional mood -isi- in conjunction with the clitic -pa yields an optative meaning, e.g. olisinpa "if I only were". Here, it is evident that the wish is not, and probably will not be fulfilled.)
In Sanskrit, the optative is formed by adding the secondary endings to the verb stem. The optative, as other moods, is known in active voice and medium voice. Examples: bhares "may you bear" (active) and bharethaas "may you bear [for yourself]" (medium). The optative may not only express wishes, requests and commands, but also possibilities, e.g. kadaacid goshabdena budhyeta "he might perhaps wake up due to the bellowing of cows"., doubt and uncertainty, e.g. katham vidyaam Nalam "how would I be able to recognize Nala?". The optative may further be used instead of a conditional mood.
The desiderative mood expresses wishes and desires. Whereas the optative expresses hopes, the desiderative expresses desires. Desires are what we want to be the case; hope generally implies optimism toward the chances of a desire's fulfillment. If someone desires something but is pessimistic about its chances of occurring, then one desires it but does not hope for it. Few languages have a distinct desiderative mood; some that do are Sanskrit and Japanese.
In Japanese the verb inflection -tai expresses the speaker's desire, e.g. watashi wa asoko ni ikitai "I want to go there". Oddly enough, this verb form is treated as a pseudo-adjective: the auxiliary verb garu is used by dropping the end -i of an adjective to indicate the outward appearance of another's mental state, in this case the desire of a person other than the speaker (e.g. Jon wa tabetagatte imasu "John wants to eat").
In Sanskrit, the infix -sa-, sometimes -isa-, is added to the replicated root, e.g. jijiivishati "he wants to live" instead of jivati "he lives". The desiderative in Sanskrit may also be used as imminent: mumuurshati "he is about to die".
The jussive mood (abbreviated jus) expresses plea, insistence, imploring, self-encouragement, wish, desire, intent, command, purpose or consequence. In some languages, the two are distinguished in that cohortative occurs in the first person and the jussive in the second or third. It is found in Arabic, where it is called the مجزوم majzūm. The rules governing the jussive in Arabic are somewhat complex.
The imperative mood expresses direct commands, requests, and prohibitions. In many circumstances, using the imperative mood may sound blunt or even rude, so it is often used with care. Example: "Paul, do your homework now". An imperative is used to tell someone to do something without argument.
In English, second person is implied by the imperative except when first-person plural is specified, as in "Let's go" ("Let us go").
The prohibitive mood, the negative imperative may be grammatically or morphologically different from the imperative mood in some languages. It indicates that the action of the verb is not permitted, e.g. "Don't go!"
In English, the imperative is sometimes used to form a conditional sentence: e.g. "Go eastwards a mile, and you'll see it" means "If you go eastward a mile, you will see it".
The admirative mood (abbreviated mir) is used to express surprise, but also doubt, irony, sarcasm, etc. In Indo-European languages, the admirative, unlike the optative, is not one of the original moods, but a later development. Admirative constructs occur in Balkan Slavic (Bulgarian and Macedonian), Tosk Albanian, and Megleno-Romanian. A form of the admirative, derived from the Albanian pattern, can be found in Frasheriote Arumanian. It seems that the dubitative/inferential patterns of Turkish — a non-Indo-European language — influenced Albanian and Balkan Slavic languages in this regard.
The cohortative mood (alternatively, "hortatory") is used to express plea, insistence, imploring, self-encouragement, wish, desire, intent, command, purpose or consequence. It does not exist in English, but phrases such as "let us" are often used to denote it. In Latin, it is interchangeable with the jussive.
The eventive mood is used in the Finnish epic poem Kalevala. It is a combination of the potential and the conditional. It is also used in dialects of Estonian. In Finnish, there are theoretically forms such as kävelleisin "I would probably walk".
Precative (abbreviated prec) mood is a grammatical mood which signifies requests, e.g. "Will you pass me the salt?"
The volitive mood (abbreviated vol) is used to indicate the desires, wishes or fears, of the speaker.
The inferential mood (abbreviated infer or infr) is used to report a nonwitnessed event without confirming it, but the same forms also function as admiratives in the Balkan languages in which they occur. The inferential mood is used in some languages such as Turkish to convey information about events, which were not directly observed or were inferred by the speaker. When referring to Bulgarian and other Balkan languages, it is often called renarrative mood; when referring to Estonian, it is called oblique mood. The inferential is usually impossible to be distinguishably translated into English. For instance, indicative Bulgarian той отиде (toy otide) and Turkish o gitti will be translated the same as inferential той отишъл (toy otishal) and o gitmiş — with the English indicative he went. Using the first pair, however, implies very strongly that the speaker either witnessed the event or is very sure that it took place. The second pair implies either that the speaker did not in fact witness it take place, that it occurred in the remote past or that there is considerable doubt as to whether it actually happened. If it were necessary to make the distinction, then the English constructions "he must have gone" or "he is said to have gone" would partly translate the inferential.
"As grammaticalized in the Balkan languages, evidentiality encodes the speaker's evaluation of the narrated event, often, but not always, predicated upon the nature of the available evidence. These evidentials can be of two types: Confirmative (sometimes called 'witnessed') and nonconfirmative (sometimes called 'reported', 'inferential', and/or 'nonwitnessed'). The nonconfirmatives can, in Austin's terms, be felicitous (neutral) or infelicitous. Felicitous nonconfirmatives are used for reports, inferences, etc., for which the speaker chooses not to take responsibility. An infelicitous nonconfirmative expresses either acceptance of a previously unexpected state of affairs (surprise, i.e. something the speaker would not have been willing to confirm prior to discovery, the mirative or admirative) or sarcastic rejection of a previous statement (doubt, irony, etc., the dubitative)."
Ibid., "Illustrative data (interlinear glossing is omitted to save space): [...]
In Bulgarian, even though a state of affairs may be entirely undisputed by the speaker, he may choose to use the renarrative in order to present disagreement with the actions or opinion of the speaker:
Grammatically, this could be seen as a way for the speaker to be demonstratively re-narrating the event (the insult) back to the listener in order for them to pause and consider their actions.
Present and future tenses also exist for such a mood in the above-mentioned languages, but, with the exception of the Albanian true nonconfirmative present illustrated above, these "nonconfirmatives, (from perfects), always have a past reference to either a real or a putative narrated event, speech event, or state of mind. They cannot be used with true nonpast reference."
Often, there is no doubt as to the veracity of the statement (for example, if it was on the news), but simply the fact that the speaker was not personally present at the event forces them to use this mood (such as the Turkish varacakmış, above, or the Bulgarian toy otishal). In this sense, the renarrative could be considered a realis mood.
It is interesting that news headlines (in Bulgaria, at least) are rarely presented in this mood, but rather in the indicative preterite - even though in most cases the reporters clearly did not witness the events being reported. 
The main body of the news report tends to use the renarrative correctly - but sometimes, again, it is intentionally avoided. This is especially so when sensitive or controversial subject matter is being dealt with. This is because, due to its ambiguity, the renarrative in such cases could be perceived as a passing of judgement or expression of doubt by the reporter, rather than as a simple renarration. In such cases, constructions with a directly-cited source reference such as "the minister said that + indicative" are preferred.