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The Latin alphabet, as well as the runic alphabets of northern Europe, the Greek alphabet and the cyrillic alphabets of eastern Europe is ultimately based on an alphabet used by the Phoenicians and Hebrews for the Phoenician and Hebrew languages.

The history of the alphabet is explained in some detail on Wikipedia. To summarise:

• The Hebrew alphabet used today and since 300 BCE is based on
  • the Aramaic alphabet used since 800 BCE which itself is based on
    • the Paleo-Hebrew alphabet used between 1000 BCE and 135 BCE which is a version of
      • the Phoenician alphabet which evolved before 1050 BCE from
        • the Proto-Sinaitic script developed from around 1700 BCE from
          • Egyptian hieroglyphs.
  • The Paleo-Hebrew alphabet has another descendant in the Samaritan alphabet used since 600 BCE.
• The Arabic alphabet is another descendant of the Aramaic alphabet.

The Hebrew, Aramaic and Arabic languages are written in this alphabet system. East-Semitic languages (Akkadian and its Babylonian and Assyrian descendants) were written in cuneiform syllabic script based on Sumerian cuneiform.

Since the Proto-Sinaitic script was developed for use with Canaanite languages (Hebrew, Phoenician and Moabite) it has symbols for all the consonants in those languages including consonants that exist in, for example, Hebrew but not in Akkadian but not for all  original Semitic consonants that survived in other Semitic languages, most notably Arabic.

Vowels were not represented by the scripts.

Aramaic is similar enough to Hebrew and Phoenician to require the same set of consonants. Hebrew and Aramaic also tend to pronounce some consonants differently depending on their relationship to nearby vowels. In some texts dots in the centre of the letters denote which of the two pronunciations is meant (but this information can usually be deduced from context).

Arabic, which preserves a larger number of the original Semitic consonants, uses the same letters and uses some of them for two distinct consonants (as opposed to distinct pronunciations of the same consonant). It uses a similar system of dots to denote which of the two pronunciations (or consonants) is meant.

(Find an Arabic version of this table and explanations here.)

The consonants in brackets are pronunciations that are known to have existed but have died out in Hebrew.

The common ancestor of Hebrew, Aramaic and Arabic was never a written language. It evolved into its daughter languages before writing was first invented.

This post was meant as in introduction. With the next post I will try to describe the consonant shifts between the Semitic ancestor of Arabic and Hebrew and the modern languages.