Unfortunately, there is not a worldwide, uniform system for record-keeping. Methods are as varied as countries, and information deemed important enough to record does not always meet the same criteria.
A great example of this problem is the English Parish Register. Unless you were part of a prominent family whose exploits were deemed worthy of preserving, no records were kept in England until 1538. It was that year that a law was passed which required the clergy in each parish to record, baptisms, marriages, and burials. It must be noted that the baptismal date, not the birth date; and the burial date, not the death date were recorded. Although it is reasonable to assume that baptism took place shortly after the birth of a child, there were exceptions, and burial at that time in history was probably done within one or two days following death.
The Parish priest or clergyman was to record these events, in a book, following the services each Sunday in the presence of the parish church warden who acted as a witness to the proceedings. Many churches complied with the new law; however, many did not, or did so in such a haphazard manner those twenty years later in 1558, another edict was sent out, and events began to be recorded sporadically.
When Queen Elizabeth I was crowned she began her reign with the decree that all existing records were to be copied into "fair parchment" books and the true parish register was created. There was considerable opposition to the demand due to the expense of the books, and the overwhelming nature of the task. Many of the clergymen began by copying the records beginning in 1538. These records were sparse and very rudimentary. Later, others tried to condense the massive amount of information by omitting large sections of the records. Of course, then as now, there was an element that ignored the law and decided to do nothing.
Some of the early records from 1538, which were rewritten in 1597, still exist, but it is not unusual for a parish register not to exist or have been preserved. Many were not kept or were lost. The registers that remain are usually stored in the county record offices, although a few are still held by individual churches. Most of these registers are "combined" registers, which means they contain all three events, baptism, marriage, and burial, recorded in the same book in chronological order. These "combined" registers were still being used in England by smaller parishes until at least the mid 1700s.
In 1754 the Hardwick Act was passed and required that everyone had to marry in the Church of England. It had to be a licensed parish church located in the couple's parish of residence. Banns, announcing intent to marry, were required to be published and read on three separate Sundays before the congregation. This would provide anyone who had any objections to the marriage taking place the opportunity to voice their objections. The publication of the banns also gave the parents of minors, anyone under twenty-one, or a previous spouse time to halt the proceedings. Jews and Quakers were exempt from the Hardwick Act, but other non-conformist were required to wed in the Church of England.
It was also during this time that the pre-printed parish register was introduced, increasing the amount of information required to be recorded, and standardizing the process. Anyone searching these later registers should pay attention to the front and back leaves of the books as well as the margins, since they were used to record other information concerning the parish such as finances, donated gifts to the church; names of the church wardens; a parishioners list; and land holdings. The register might also contain items of local interest such as descriptions of the whether, damage and repairs to the buildings or even the occurrence of natural disasters.
Even with the treasure trove of information a parish register provides, there are several drawbacks and features that should be noted by the researcher. Date of birth rarely appeared in baptismal registers until about the 1860s, unless the person being baptized was an adult. Also, Church of England registers did not record Godparents' names. It was a common practice, especially in early registers, for the mother's name not to be mentioned. It was a masculine world and the female of the species was not considered to be as important as the male. Many times the mother is left off completely or addressed simply as "and his wife." Later on her first name began to be recorded on the baptismal record. If a child was illegitimate the mother's full name was used along with the label, illegitimate, base, bastard, or spurious, was written in the margin. Some clergymen would get even more descriptive and might record "bastard son of the whore Mary Smith." Always check those margin notes.
Before 1754 only the bride's and groom's names were mentioned on a marriage record, unless they were from a different parish than the one where the marriage took place; and although parents names were not recorded, many times they were witnesses to the marriage.
Remember, this is not necessarily the parish of their birth but the parish of residence at the time of the marriage. It was also possible to get a dispensation to marry by license in a parish outside the one where the couple resided, and no banns were required to be read or published. The opportunity for persons to object to the event was still followed, but took place at the beginning of the ceremony. After 1837 it was possible to marry in a register office, licensed non-conformist chapel, or Catholic Church.
Genealogical research requires more than just collecting dates, names, and places. A great deal of background work is also involved. Familiarity with record keeping practices is an essential element. This is only a sample of what will be found when using the English parish register, but shows the importance of understanding the history of record-keeping in the area of your search.