文字就係符號嘅一種，用嚟表示概念、記綠口語、事、物，用作人同人溝通嘅一種媒介。

歷史
最古老嘅文字主要都係基於象形符號同埋表意符號呢啲元素嘅自然語標。大部分書寫系統都可以廣泛噉歸為三個類別：語標、 音節 同埋 字母 （亦或係 segmental）；之但係，各種變化性好大嘅書寫系統入便是但揀出嘅任何一種，呢三種類別通通都可以喺其中搵倒。噉樣就通常就好難單一分類某一種書寫系統。嗰啲語標、音節同埋字母三者相混，好難分類嘅系統就經常用複雜系統嚟描述。

書寫系統嘅種類
主文： 意音文字
A logogram is a single written character which represents a complete grammatical word. Most Chinese characters are classified as logograms.
每個符號代表一個字，準確啲係代表一個語素， many logograms are required to write all the words of language. The vast array of logograms and the memorization of what they mean are the major disadvantage of the logographic systems over alphabetic systems. However, since the meaning is inherent to the symbol, the same logographic system can theoretically be used to represent different languages. In practice, this is only true for closely related languages, like the Chinese languages, as syntactical constraints reduce the portability of a given logographic system. Japanese use Chinese logograms extensively in its writing systems, with most of the symbols carrying the same or similar meanings. However, the semantics, and especially the grammar, are different enough that a long Chinese text is not readily understandable to a Japanese reader without any knowledge of basic Chinese grammar, though short and concise phrases such as those on signs and newspaper headlines are much easier to comprehend.
While most languages do not use wholly logographic writing systems many languages use some logograms. A good example of modern western logograms are the Hindu-Arabic numerals — everyone who uses those symbols understands what 1 means whether he or she calls it one, eins, uno, yi, ichi or ehad. Other western logograms include the ampersand &, used for and, the at sign @, used in many contexts for at, the percent sign % and the many signs representing units of currency ($, ¢, €, £, ¥ and so on.)
Logograms are sometimes called ideograms, a word that refers to symbols which graphically represent abstract ideas, but linguists avoid this use, as Chinese characters are often semantic–phonetic compounds, symbols which include an element that represents the meaning and element that represents the pronunciation. Some nonlinguists distinguish between lexigraphy and ideography, where symbols in lexigraphies represent words, and symbols in ideographies represent words or morphemes.
The most important (and, to a degree, the only surviving) modern logographic writing system is the Chinese one, whose characters are used, with varying degrees of modification, in Chinese, Japanese, Korean, Vietnamese, and other east Asian languages. Ancient Egyptian hieroglyphics and the Mayan writing system are also systems with certain logographic features, although they have marked phonetic features as well, and are no longer in current use.
See List of writing systems for a list of predominantly-logographic writing systems.

意音文字
主文： 音節文字
As logographic writing systems use a single symbol for an entire word, a syllabary is a set of written symbols that represent (or approximate) syllables, which make up words. A symbol in a syllabary typically represents a consonant sound followed by a vowel sound, or just a vowel alone. In a true syllabary there is no systematic graphic similarity between phonetically related characters (though some do have graphic similarity for the vowels). That is, the characters for "ke", "ka", and "ko" have no similarity to indicate their common "k"-ness. Compare abugida, where each grapheme typically represents a syllable but where characters representing related sounds are similar graphically (typically, a common consonantal base is annotated in a more or less consistent manner to represent the vowel in the syllable).
Other languages that use syllabic writing include Mycenaean Greek (Linear B) and Native American languages such as Cherokee. Several languages of the Ancient Near East used forms of cuneiform, which is a syllabary with some non-syllabic elements.
See List of writing systems for a list of syllabaries.

字母
主文： Abugida
An abugida is an alphabetic writing system whose basic signs denote consonants with an inherent vowel and where consistent modifications of the basic sign indicate other following vowels than the inherent one.
Thus, in an abugida there is no sign for "k", but instead one for "ka" (if "a" is the inherent vowel), and "ke" is written by modifying the "ka" sign in a way that is consistent with how one would modify "la" to get "le". In many abugidas the modification is the addition of a vowel sign, but other possibilities are imaginable (and used), such as rotation of the basic sign, addition of diacritical marks, and so on.
The obvious contrast is with syllabaries, which have one distinct symbol per possible syllable, and the signs for each syllable have no systematic graphic similarity. The graphic similarity comes from the fact that most abugidas are derived from abjads, and the consonants make up the symbols with the inherent vowel, and the new vowel symbols are markings added on to the base symbol.
The Ethiopic script is an abugida, although the vowel modifications in Ethiopic are not entirely systematic. Canadian Aboriginal Syllabics can be considered abugidas, although they are rarely thought of in those terms. The largest single group of abugidas is the Brahmic family of scripts, however, which includes nearly all the scripts used in India and Southeast Asia.
The name abugida is derived from the first four characters of an order of the Ge'ez script used in some religious contexts. The term was coined by Peter T. Daniels.
See List of writing systems for a list of abugida-based writing systems.

Abugida
主文： 輔音字母
The first type of alphabet that was developed was the abjad. An abjad is an alphabetic writing system where there is one symbol per consonant. Abjads differ from regular alphabets in that they only have characters for consonantal sounds. Vowels are not usually marked in abjad.
All known abjads (except maybe Tifinagh) belong to the Semitic family of scripts, and derive from the original Northern Linear Abjad. The reason for this is that Semitic languages and the related Berber languages have a morphemic structure which makes the denotation of vowels redundant in most cases.
Some abjads (like Arabic and Hebrew) have markings for vowels as well, but only use them in special contexts, such as for teaching. Many scripts derived from abjads have been extended with vowel symbols to become full alphabets, the most famous case being the derivation of the Greek alphabet from the Phoenician abjad. This has mostly happened when the script was adapted to a non-Semitic language.
The term abjad takes its name from the old order of the Arabic alphabet's consonants Alif, Bá, Jim, Dál, though the word may have earlier roots in Phoenician or Ugaritic.
Abjad is still the word for alphabet in Arabic, Malay, and Indonesian.
See List of writing systems for a list of abjad-based writing systems.

輔音字母
A featural script represents finer detail than an alphabet. Here symbols do not represent whole phonemes, but rather the elements (features) that make up the phonemes, such as voicing or its place of articulation. Theoretically, each feature could be written with a separate letter; and abjads or abugidas, or indeed syllabaries, could be featural, but the only prominent system of this sort is Korean Hangul. In Hangul, the featural symbols are combined into alphabetic letters, and these letters are in turn joined into syllabic blocks, so that the system combines three levels of phonological representation.

寫字方向

decodeunicode 50,000 glyphs, Unicode Wiki
About African writing systems by the John Henrik Clarke Africana Library at Cornell University:

• http://www.library.cornell.edu/africana/Writing_Systems/Welcome.html
  General about writing systems
  
  
  
  • Omniglot
    Alphabetic Writing Systems
    Michael Everson's Alphabets of Europe
    The Unicode Consortium