|Types of Writing Systems|
Writing systems can be conveniently classified into broad "types" depending on the way they represent their underlying languages.
A system of this kind uses a tremendous number of signs, each to represent a morpheme. A morpheme is the minimal unit in a language that carries some meaning. So, a logogram, a sign in a logographic system, may represent a word, or part of a word (like a suffix to denote a plural noun). Because of this, the number of signs could grow to staggering numbers like Chinese which has more than 10,000 signs (most of them unused in everyday usage).
This is somewhat like a stripped down versions of logographic systems. In essence, there are two major types of signs, ones denoting morphemes and ones denoting sounds. Most of the logophonetic systems are logosyllabic, meaning that their phonetic signs mostly denote syllables. An exception is Egyptian, whose phonetic signs denote consonants.
In a syllabic writing system, the overwhelming number of signs are used solely for their phonetic values. These phonetic signs are Syllabograms, meaning that they represent syllables rather than individual sound. A few non-phonetic are used for numbers, punctuation, and commonly used words.
Consonantal Alphabet or Abjad
Consonantal alphabets are also known as abjads, and are all descendents of the Proto-Sinaitic script. In a "pure" consonantal alphabet, vowels are not written. However, nearly consonantal alphabets use certain conventions to
Syllabic Alphabet or Abugida
South Asian scripts such as Brahmi and its descendents fit into both syllabary and alphabet. It is syllabic because the basic sign contains a consonant and a vowel. However, every sign has the same vowel, such as /a/ in Brahmi. To make syllables with a different vowel, you add special markings to the basic sign, which is somewhat like an alphabet. Hence the name "syllabic alphabet".
Nearly all the sounds in a language can be represented by an appropriate consonant and vowel alphabet. However, just take a look at English spelling and you can almost feel we"re back to logographic systems :) !