A verb is in the subjunctive mood when it expresses a condition which is doubtful or not factual. It is most often found in a clause beginning with the word if. It is also found in clauses following a verb that expresses a doubt, a wish, regret, request, demand, or proposal.
These are verbs typically followed by clauses that take the subjunctive:
ask, demand, determine, insist, move, order, pray, prefer, recommend, regret, request, require, suggest, and wish.
In English there is no difference between the subjunctive and normal, or indicative, form of the verb except for the present tense third person singular and for the verb to be.
The subjunctive for the present tense third person singular drops the -s or -es so that it looks and sounds like the present tense for everything else.
The subjunctive mood of the verb to be is be in the present tense and were in the past tense, regardless of what the subject is.
Incorrect: If I was you, I would run.
Correct: If I were you, I would run.
(The verb follows if and expresses a non-factual condition.)
Incorrect: I wish he was able to type faster.
Correct: I wish he were able to type faster.
(The second verb is in a clause following a verb expressing a wish. It also suggests a non-factual or doubtful condition.)
Incorrect: His requirement is that everyone is computer literate.
Correct: His requirement is that everyone be computer literate.
(Subordinate clause follows main clause with a demand.)
Incorrect: He recommended that each driver reports his tips.
Correct: He recommended that each driver report his tips.
Sometimes we may use the conditional auxiliary verbs of could, should, or would to express the same sense.
Subjunctive:I wish he were kinder to me.
Conditional: I wish he would be kinder to me.
Note: In modern English, the subjunctive is found only in subordinate clauses.