Baptism details are recorded in church registers whenever a person, usually a child, is baptised or christened. They usually include information about the parents, and sometimes god-parents, and often the date of birth of the child.
For family historians researching ancestors in the UK, the most useful entries are those of Parish Churches before the middle of 1837. After then the formal registration of births provides Birth Certificates that usually give more reliable information.
- England & Wales Parish Registers by Family Tree Resources