Any verb has a mood, a voice and a tense. The mood will be indicative, imperative. infinitive etc. Voice will be either active or passive. Tense will be present, future, past,perfect,pluperfect, future perfect etc?
How does subjunctive fit into this schema? What is the alternative called?
I find it difficult to understand it as a mood, since any subjunctive verb is written indicatively, which is a mood in its own right.
E.G. If I were rich, I would travel widely
Later edit I can now see from comments and answers that the above sentence is not indicative (which is effectively its opposite and something I should have realised). Though I also appreciate that if one accepts John Lawler's dictum there is no subjunctive in English.
Best Answer
You're confusing traditional Latin grammar terminology with English grammar terminology,
and with modern linguistic terminology, as well.
Mood, Voice, and Tense were traditional inflectional categories of Latin verbs. I.e,
every verb in Latin was inflected (marked uniquely) for some mix of mood, voice, and tense.
Latin had six tenses (by a strange coincidence the same six you listed),
four moods (indicative, subjunctive, imperative, and interrogative),
and two voices (active and passive). That was Latin.
English has two tenses (Present and Past), no moods, and no voices.
In particular, English has no subjunctive mood, so you don't have to worry about it any more.
However, many other languages have rich inflectional systems, even richer than Latin.
Sanskrit and Greek both had a Middle Voice as well as Active and Passive, for instance,
and an Optative Mood (used for things one wishes and hopes for), and Sanskrit also had a Benedictive Mood (used for blessings).
And that's just Indo-European. There are lots of other ways to organize these matters.