Tajiki is the name given to the Persian dialect spoken by the people of Tajikistan and Uzbekistan. Of note is the fact that the Tajiki spoken by the average Tajik is very different from literary Tajik. This difference is so significant that a native my mistake spoken literary Tajiki for Farsi.
Before Tajikistan was made a part of the old Soviet Union, the script had an Arabic base, but subsequently, a Cyrillic script was reintroduced and is the de facto script used and understood by most people in Tajikistan today. The Tajiks are ‘keepers’ of thousand-year-old traditions relating to the culture of the Persian speaking area, dating back to Medieval times.