Where did my ancestors come from, what was the name of my first known ancestor, where did he live and what did he do, how long did he live? The most reliable answers to these and similar questions are offered by registers. These registers are interesting for laymen exploring their family trees but they are also a first-class source for analyzing the history of a micro community and for studying demography.

Originally, registers are public documents whose task is to legitimately testify facts that they record, primarily, birth, marriage and death. Because of their legal force they are a reliable source for various branches of science. They contain information about the birth rate, the mortality rate, migration tendencies, social and class structure of a population and they offer information about average life expectancy, the mortality rate of newborns and the ethnic composition of population. The languages used in Registers are Latin and Italian and partly Croatian and German. The script is mainly Latin but there are also some documents written in the Glagolitic Script. In the parish of Peroj documents have been written in the Cyrillic script since 1861

It is impossible to exactly define when people started recording the first registers in Istria, but if we look at the preserved registers, we can say that it was quite early. This can be proved by the fact that in the State Archives in Pazin and in some parish offices there are books which were written before the Decree of the Trent Council (1563) and the Roman Ritual (Rituale Romanum) from 1614. Based on how old the preserved books are and their integrity, Istria holds the top spot in Croatia. The number of books that are recorded in parish offices, registries and local offices together with those in the State Archives in Pazin exceeds 2000. Given the fact that a lot of books have disappeared, due to wars and other destructions of archival material, and that the catalogues of preserved books have not been finished yet, we can say that this is a highly respectable holding of registers which represent a first-class and reliable historical source. We must also mention the transcripts that have been collected in the Bishop Ordinariate in Poreč since 1835 and in the Bishop Ordinariate in Trieste (until 1943) which say a lot about the preservation of the registers in Istria. The list of registers was published in Vjesnik istarskog arhiva, volumes 11-13 (2004-2006).