I plucked this article from Wikipedia and I thought it was particularly interesting as it discusses the formation of the Tibetan script, the development and what it is today. I was told that the Tibetan script was developed from a variant of Sanskrit and was created to facilitate the translation and transfer of Indian Buddhist texts.
The Tibetan alphabet is an abugida of Indic origin used to write the Tibetan language as well as the Dzongkha language, Denzongkha, Ladakhi language and sometimes the Balti language. The printed form of the alphabet is called uchen script (Wylie: dbu-can; "with a head") while the hand-written cursive form used in everyday writing is called umê (Wylie: dbu-med; "headless"). The alphabet is very closely linked to a broad ethnic Tibetan identity. Besides Tibet, it has also been used for Tibetan languages in Bhutan, India, Nepal, and Pakistan. The Tibetan alphabet is ancestral to the Limbu alphabet, the Lepcha alphabet, and the multilingual 'Phags-pa script.
The Tibetan alphabet is romanized in a variety of ways. This article employs the Wylie transliteration system.
History
The creation of the Tibetan alphabet is attributed to Thonmi Sambhota of the mid-7th century. Tradition holds that Thonmi Sambhota, a minister of Songtsen Gampo (569-649), was sent to India to study the art of writing, and upon his return introduced the alphabet. The form of the letters is based on an Indic alphabet of that period.
Three orthographic standardizations were developed. The most important, an official orthography aimed to facilitate the translation of Buddhist scriptures, emerged during the early 9th century. Standard orthography has not altered since then, while the spoken language has changed by, for example, losing complex consonant clusters. As a result, in all modern Tibetan dialects, in particular in the Standard Tibetan of Lhasa, there is a great divergence between spelling (which reflects the 9th-century[contradictory] spoken Tibetan) and pronunciation. This divergence is the basis of an argument in favour of spelling reform, to write Tibetan "as it is pronounced", for example, writing "Kagyu" instead of "Bka'-rgyud". In contrast, the pronunciation of the Balti, Ladakhi and Burig languages adheres more closely to the archaic spelling.
Description
The Tibetan alphabet has 30 consonants, sometimes known as radicals, which are the basis of the script.
Polychrome text left of center is the primary mantra of Tibetan Buddhism, Sanskrit O? Ma?i Padme H?? (Wylie: oMmanipad+mehU~M). Monochrome text right of center reads Sanskrit "O? Vajrasattva H?m" (Wylie: oM badzrasatwa hUM), an invocation to the embodiment of primeval purity.
As in other Indic scripts, each consonant letter assumes an inherent /a/. However, a unique aspect of the Tibetan script is that the consonants can be written either as radicals, or they can be written in other forms, such as superscripts and subscripts. The superscript position above a radical is reserved for the consonants r, l, and s, while the subscript position under a radical is for the consonants y, r, l, and w. To understand how this works, one can look at the radical "ka" and see what happens when it becomes "kra" or "rka". In both cases, the symbol for "ka" is used, but when the r is in the middle of the consonant and vowel, it is added as a subscript. On the other hand, when the r comes before the consonant and vowel, it is added as a superscript. R actually changes form when it is above most other consonants; thus rka. However, an exception to this is the cluster rnya. Similarly, the consonants w, r, and y change form when they are beneath other consonants; thus kwa; kra; kya.
Besides being written as subscripts and superscripts, some consonants can also be placed in prescript, postscript, or post-postscript positions. For instance, the consonants g, d, b, m, and ’a ("’a chung") can be used in the prescript position to the left of other radicals, while the position after a radical (the postscript position), can be held by the ten consonants g, n, b, d, m, ’a, r, n?, s, and l. The third position, the post-postscript position, is solely for the consonants d and s.
The vowels used in the alphabet are a, i, u, e, and o. While the vowel a is included in each consonant or radical, the other vowels are indicated by marks; thus ka, ki, ku, ke, ko. The vowels i, e, and o are placed above consonants as diacritics, while the vowel u is placed underneath consonants. Old Tibetan included a gigu 'verso' of uncertain meaning. There is no distinction between long and short vowels in written Tibetan, except in loanwords, especially transcribed from the Sanskrit.
In the Tibetan script, the syllables are written from left to right. Syllables are separated by a tseg (?); since many Tibetan words are monosyllabic, this mark often functions almost as a space. Spaces are not used to divide words.
Although some Tibetan dialects are tonal, the language had no tone at the time of the script's invention, and there are no dedicated glyphs for tone. However, since tones developed from segmental features they can usually be correctly predicted by the archaic spelling of Tibetan words.
As in other Indic scripts, clustered consonants are often stacked vertically. Unfortunately, some fonts and applications do not support this behavior for Tibetan, so these examples may not display properly; you might have to download a font such as Tibetan Machine Uni.