datieren
to date
To put a date on a document, letter, or work of art in order to record the time of its creation.
Bitte vergiss nicht, den Vertrag zu unterschreiben und zu datieren.
Please don't forget to sign and date the contract.

to date
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to date
To put a date on a document, letter, or work of art in order to record the time of its creation.
Bitte vergiss nicht, den Vertrag zu unterschreiben und zu datieren.
Please don't forget to sign and date the contract.

The verb 'datieren' (to date) is derived directly from the noun 'das Datum' (date). It describes the action connected with a date: either setting a date or determining the date of something.
Der Experte konnte das Gemälde genau datieren.
The expert was able to date the painting precisely.
The use of prepositions depends on the sentence construction. When a person determines the age, it is 'etwas auf [Akkusativ] datieren' (to date something to [accusative]). When an object comes from a time, it is 'etwas datiert aus [Dativ]' (something dates from [dative]).
Forscher datieren die Ruinen auf das 12. Jahrhundert.
Researchers date the ruins to the 12th century.
'Datieren' (to date) is a rather formal word that is often found in written language, scientific texts, or official documents. It is used less often in everyday conversation.
Alle offiziellen Dokumente müssen datiert und unterschrieben werden.
All official documents must be dated and signed.
In this meaning, the verb is active: a person or institution (e.g., archaeologists, experts) is the subject that performs the action of dating. By contrast, in the meaning 'stammen aus' (to come from/date from), the object itself is the subject of the sentence.
Ein Team von Geologen datiert die Gesteinsschicht auf ein Alter von zwei Millionen Jahren.
A team of geologists dates the rock layer to an age of two million years.
to write
'schreiben' and 'datieren' can both refer to a date on a document. Here, 'schreiben' is very general: you simply write a date, a number, or a text. 'datieren' is more precise and more formal. It means putting a date on a document, letter, or work of art so it is clear when it was created. Learners may confuse the words because when you 'datieren' something, you also write a date. In normal everyday situations, people usually say 'das Datum schreiben' (to write the date). 'datieren' is more suitable for official documents, letters, or works of art.

Die Mitarbeiterin datiert den Vertrag, bevor beide Seiten unterschreiben.
The employee dates the contract before both parties sign it.
Schreibst du bitte das heutige Datum oben auf das Formular?
Could you please write today's date at the top of the form?