Although many writing systems have been developed over the years and across the world, relatively few are still in use. As the Wikipedia map posted below shows, most countries today use either the Latin, Arabic, or Cyrillic scripts for their own national (or major regional) languages. Only a handful or countries have their own unique scripts that are used to write their own national and official languages. Determining which countries fall into this category – shown on the second map below – is somewhat tricky. The Hangul script, for example, is unique to the Korean language and nation, but that nation is divided into two states: North Korea and South Korea. The Greek alphabet is essentially limited to the Greek language, but Greek is the national tongue of two countries, Greece and the Republic of Cyprus (although the break-way Turkish Republic of Northern Cyprus uses the Latin alphabet). The Ethiopic script, or Ge’ez, is employed for official purposes only in Ethiopia, but is also used extensively in neighboring Eritrea (along with the Latin and Arabic scripts). I have included all three of these scripts in the map below. I did not, however, include the Chinese writing system, because it is also used in three countries other than China (exclusively in Taiwan, alongside the Latin and Tamil scripts in multi-lingual Singapore, and in combination with two indigenous scripts [hiragana and katakana] in Japan).
Other than Israel (which uses the Hebrew script), the remaining countries with their own unique scripts used to write their national languages are located either in mainland Southeast Asia (Burma/Myanmar, Thailand, Laos, and Cambodia) or the Caucasus (Georgia and Armenia). In the Caucasus, the Georgian language stands out for having three separate scripts of its own: Mkhedruli, Asomtavruli, and Nuskhuri. Mkhedruli was at one time the country’s “royal script,” but is now used for almost all secular writing. The Georgia Orthodox Church, however, still uses the other alphabets in “ceremonial religious texts and iconography.” As a result, the “living culture of three writing systems of the Georgian alphabet” was granted the national status of intangible cultural heritage in Georgia in 2015 and inscribed on the UNESCO Representative List of the Intangible Cultural Heritage of Humanity in 2016” (direst quotation from this Wikipedia article).
(The Wikipedia table above above shows only 14 of 33 letters in the 33 letters of the current Georgian alphabet.)
Today, the Georgian script (Mkhedruli) used mainly for the Georgian language, but it is also sometimes employed for the three related Kartvelian languages of northwestern Georgia and northeastern Turkey: Mingrelian, Svan,* and Laz. When the Georgian script is used to write Mingrelian and Svan, three additional letters are employed. Svan and Laz are rarely written, however, and Laz is now also expressed in a modified Latin alphabet and may at any rate be dying out as a spoken language. In earlier times, Georgian scripts had been used for several unrelated languages of the Caucasus, including Chechen, Ossetian, Abkhazian, and Avar. As this example shows, Georgian culture was historically influential over a much larger area than that currently included within the Republic of Georgia.
*Despite their different languages, Mingrelian and Svan speakers are counted as ethnic Georgians, and almost are fluent in Georgian and generlly employ Georgian when writing.