A written statement of fact, sworn before a Commissioner for Oaths and signed by you.
It is the everyday instrument of Ghanaian bureaucracy. The most common use is the name discrepancy: your birth certificate says one spelling, your school certificate another, your bank a third. A declaration states that all of them refer to one person, and institutions accept it.
It is also used to declare a date of birth where no record exists, to support a late birth registration, to report a lost document, and to declare a change of name.
Swearing something false in one is an offence. That is what gives it its weight.