| The above write-ups refer primarily to Modern Hebrew, the language of modern Israel. Before that, for about 2000 years, Hebrew was a "dead" language (see note at end), though preserved for liturgical and literary functions. Before that, back in the Biblical period when it was originally a living language, the alphabet was something like this:
?âlep, bêt, gimel, dâlet, hê, wâw, zayin, h!êt, t!êt, yod, kap, lâmed, mêm, nun, sâmek, &ayin, pê, s!âdê, qop, rêsh, shin, tâw.
Each of these 22 is a consonant. I am using the following special symbols for six of the consonants: ? h! t! & s! sh, the same system as in my write-up on Arabic pronunciation.
But the vowels weren't written until almost a thousand years after the consonants: by Jewish scholars called Masoretes preserving the traditional pronunciation. They also indicated some shades of pronunciation in the consonants present in their own day. And this tradition continued right up until the time Hebrew was resurrected as a fully living language last century.
There were seven distinct vowel signs in Ancient Hebrew: I am using the extra symbols â ê for two of them. So these are not length marks here. It is debatable whether this represented a five-vowel system with significant length, or a seven-vowel system where length was less important; possibly there were two distinct traditions. Some of the consonants indicated vowel length in the oldest texts, and probably still did when the rest of the vowels got inserted.
So what is studied as Biblical Hebrew is normally a hybrid, the consonants of 1000-500 BCE, the vowels of 500-1000 CE, and in fact the European pronunciation of that from about 1500-2000. (Modern Hebrew has been filtered through the sound systems of German, Polish, and/or Russian, and lost its characteristically Semitic sounds.) (Later. Aha, TheLady below makes a valuable contribution to my very small knowledge of Modern Hebrew.)
The consonant ? ?âlep (yes I do mean a question mark) was a glottal stop, as in the London no? a lo? "not a lot". The sound & &ayin was the indescribable pharyngeal fricative, and h! h!êt was its voiceless counterpart, like h with the throat constricted. Both of these still occur in Arabic and Somali, but have disappeared from Modern Hebrew. (Again, see TheLady's correction of my ignorance under this.)
The q qop was a uvular stop; and the t! t!êt was probably a pharyngealized t; both also still occur in Arabic.
The six consonants b g d k p t had by the Masoretic period acquired two variants: single between vowels, and finally, they were fricatives v gh dh kh f th (where dh is as in then, kh as in loch). The Masoretes marked these distinctions with points (dots) inside the consonants: whence the usual spellings aleph, beth, daleth etc.
The waw was w as in English, not the v of modern Hebrew; when it changed to this sound it therefore merged with the fricative variety of b.
The sibilants sâmek, s!âdê, shin are problematic. The simplest possibility is that they were respectively s as in English see, emphatic (pharyngealized) s! as in Arabic, and sh as in English shin. However, the Masoretes had to use points to split shin into two different letters, and called one of them sin: it apparently had the plain s sound the same as sâmek. Perhaps the texts were first written in a dialect that didn't have a distinct sin sound. It is now thought likely (by comparison with other Afro-Asiatic languages) that sin originated from a lateral fricative like Welsh ll.
Also, the s! sound later developed into a ts sound (as in Modern Hebrew, also written tz). It might have had this sound quite early. The name Yis!h!aq contains four consonants none of which occurred in Ancient Greek: it was transliterated in the Septuagint as Isaak. This suggests it had not yet become ts, because they could have written Itsaak in Greek.
This is just the alphabet. Under one or more nodes yet to be written I intend to go into details of the Ancient and the Traditional (Masoretic) pronunciations, and the differences between them.
* On "dead" languages: this traditional designation is too crude. Linguists don't have any official terminology to clarify the point, but some "dead" languages, cardinally Hebrew, Latin, and Sanskrit, had no native speakers for between one and two thousand years but were nevertheless widely and fluently used by a large community of people who learnt them as a second language. Though they did not evolve at the same rate as languages learnt in the cradle, they nevertheless changed historically too.
There is a butterfly called Hebrew letter because of its marking. | 
