Dze (Ѕ ѕ; italics: "Ѕ ѕ") is a letter of the Cyrillic script, used in the Macedonian alphabet to represent the voiced alveolar affricate , similar to the pronunciation of ⟨ds⟩ in "needs" or "kids" in English. It is derived from the letter "dzelo" or "zelo" of the Early Cyrillic alphabet, and it was used historically in all Slavic languages that use Cyrillic.
Although fully obsolete everywhere in the Cyrillic world by the 19th century, the letter "zelo" was revived in 1944 by the designers of the alphabet of the then-codified Macedonian language. The phoneme is also present in Greek ("ΤΖ" τζ) and Albanian (X x), both non-Slavic neighbours to the Macedonian language; all are a part of the Balkan linguistic area. In the early 21st century, the same letter also appeared in Vojislav Nikčević's proposal for the new alphabet for the modern Montenegrin language. 
The most common early letterform (Ѕ ѕ) resembles the Latin letter S (S s), but it is also seen reversed (Ꙅ ꙅ) like the Latin letter Reversed S (Ƨ ƨ), or Z with a tail and a tick (Ꙃ ꙃ).
Abkhaz has Abkhazian Dze (Ӡ ӡ), with an identical function and name but a different shape.
Church Slavonic.
The letter is descended from ѕѣло (pronounced "dzělo"; ) in the Early Cyrillic alphabet, where it had the numerical value 6. The letter Dzělo was itself based on the letter Dzelo in the Glagolitic alphabet. In the Glagolitic alphabet, it was written ⟨Ⰷ⟩, and had the numerical value of 8. In Old Church Slavonic it was called ѕѣло (pronounced "dzeló"), and in Church Slavonic it is called ѕѣлѡ (pronounced "zeló").
The origin of Glagolitic letter Dzelo is unclear, but the Cyrillic Ѕ may have been influenced by the Greek stigma ⟨Ϛ⟩, the medieval form of the archaic letter digamma, which had the same form and numerical value (6). Thus the visual similarity of the Cyrillic ⟨Ѕ⟩ and Latin ⟨S⟩ is largely coincidental.
The initial sound of ⟨Ѕ⟩ in Old Church Slavonic was a soft or , which usually came from a historically palatalised *g (ноѕѣ, ѕвѣзда, etc.). In almost all Slavic dialects this sound was pronounced as a simple /z/; however, as the Old Church Slavonic language was based on the Bulgaro-Macedonian dialects, the sound remained distinct. 
In the Old Slavic period the difference between ⟨Ѕ⟩ and ⟨З⟩ had already begun to be blurred, and in the written Church Slavonic language from the middle of the 17th century ⟨Ѕ⟩ was used only formally. The letter's distinguishing features from ⟨З⟩ are:
"See also Reforms of Russian orthography".
East Slavic Languages.
In Russian it was known as зѣло or "zelo" and had the phonetic value of or . In the initial version of Russian civil script of Tsar Peter I (1708), the ⟨Ѕ⟩ was assigned the sound , and the letter ⟨З⟩ was removed. However, in the second version of the civil script (1710), ⟨З⟩ was restored, and ⟨Ѕ⟩ was abolished. Both versions of the alphabet were used until 1735, which is considered the date of the final elimination of ⟨Ѕ⟩ in Russian.
In Ukrainian, the sound is integrated as part of the language's phonology, but it mainly occurs in loanwords rather than in words of native Ukrainian origin. As such, the digraph ⟨дз⟩ is used to represent both the phoneme and the separately occurring consonant cluster which Ukrainian phonotactics assimilate as .
Belarusian commonly features ⟨дз⟩, but it usually comes from *d from a similar development to Polish. As such, ⟨ѕ⟩ had never been used for it.
South Slavic Languages.
⟨ѕ⟩ is now only used in the Macedonian alphabet. A commission formed to standardise the Macedonian language and orthography decided to adopt the letter on December 4, 1944, after a vote of 10-1. Despite the letter originally being found between ⟨ж⟩ and ⟨з⟩, in the new alphabet it was placed after ⟨з⟩ instead. The letter represents (examples including: ѕид/"dzid", 'wall' and ѕвезда/"dzvezda", 'star'). The corresponding sound is used in all dialects of Macedonian.
⟨ѕ⟩ was also used to the middle of the 19th century in the Serbian civil script, whose orthography was closer to Church Slavonic (compared to Russian). Vuk Karadžić's Serbian Cyrillic alphabet (1868) did not include ⟨ѕ⟩, instead favouring a simple digraph ⟨дз⟩ to represent the sound, as it was non-native. ⟨Ѕ⟩ is also included in Microsoft's Serbian Cyrillic keyboard layout, although it is not used in the Serbian Cyrillic Alphabet. The Serbian keyboard in Ubuntu replaces Ѕ with a second Ж.
Modern Bulgarian, apart from when explicitly written with the Church Slavonic alphabet, has never used ⟨ѕ⟩. Although most dialects feature it, it is found in neither the Tărnovo dialect, the prestige dialect of the time of codification, nor in the Church Slavonic language (despite being written independently there). A few eastern dialects, including the Tărnovo dialect, have, however, independently developed both /dz/ and /dʒ/ phonemes not found in the standard language due to affrication. Marin Drinov, one of the most important players in the establishment of Standard Bulgarian, floated the idea of using ⟨ѕ⟩ as it was found in most dialects, however chose not to as he considered the letter all but forgotten.
The Banat Bulgarian dialect, being based on the Paulician dialect, retains ⟨ѕ⟩. However, as it is written with the Latin script, the sound is instead notated as ⟨dz⟩.
Romanian.
⟨ѕ⟩ was used in the Romanian Cyrillic alphabet (where it represented ) until the alphabet was abolished in favour of a Latin-based alphabet in 1860-62.
References.
 ;templatestyles src="Reflist/styles.css" / ;