The most important source of knowledge for family history researchers are definitely registries, also called parish books, in Czech matriky. This word comes from Latin matricula, which means list of priests
The oldest Czech registries are from 16th century - the oldest ones comes from mid of 16th century. But these are exceptions - the need to have the registries wasn't too strong until the 30 years war and recatolization of Czech lands.
First parish books were just lists created by the vicar to have an overview about his herd. But as the time went, there were more and more information mentioned in the records. However the amount of information depended only on the person which was writing into the registry - therefor some records are very short, other are long and in rich language.
Registries became official documents in 1784, during the reign of Emperor Josef II. It was strictly set what content the records has to have. This unfortunately meant shortening of the records in many cases, because some vicars stopped to write down information included before (as father's name, village of origin etc.). Mandatory content of the records was extended in the following decades until the records included quite many information - occupation, information about parents or grandparents, where were they from and so on. I'll introduce you different time periods in special posts.
Note about evangelical churches:
New evangelical churches and registries were also founded after 1782. You can find duplicate records both in catholic and evangelical registries for the time period of 1784-1832, but after this year the churches were totally splitted and the catholic vicars didn't write information about evangelics into catholic books anymore.