vertreten
to stand in for
To act for someone or be present in their place; to represent someone or function as a substitute.
Mein Kollege wird mich während meines Urlaubs vertreten.
My colleague will stand in for me during my vacation.

to represent
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to stand in for
To act for someone or be present in their place; to represent someone or function as a substitute.
Mein Kollege wird mich während meines Urlaubs vertreten.
My colleague will stand in for me during my vacation.

'Vertreten' (to represent / to stand in for) is an inseparable verb. The prefix 'ver-' remains firmly attached to the verb stem 'treten' in all sentence forms and tenses.
Er vertrat seine Meinung sehr überzeugend.
He represented his opinion very convincingly.
When you step in for another person or represent them, that person is the direct object in the accusative.
Der Anwalt vertritt seinen Mandanten vor Gericht.
The lawyer represents his client in court.
To express that you hold a particular view, 'vertreten' is often combined with nouns such as 'Meinung' (opinion), 'Standpunkt' (position/point of view), 'Ansicht' (view), or 'Position' (position).
Ich vertrete den Standpunkt, dass wir nachhaltiger leben müssen.
I hold the position that we need to live more sustainably.
In the meaning 'to be present', this verb is almost always used in a passive-like construction with 'sein' (to be) and the past participle 'vertreten'.
In der Ausstellung sind viele bekannte Künstler vertreten.
Many well-known artists are represented in the exhibition.
The idiom 'sich die Beine vertreten' (to stretch one's legs) is a fixed unit. The pronoun 'sich' is in the dative here, and 'die Beine' is in the accusative.
Lass uns kurz anhalten, damit wir uns die Beine vertreten können.
Let's stop briefly so we can stretch our legs.
to replace / reimburse
'vertreten' and 'ersetzen' can both mean that someone or something takes the place of someone or something else. The difference lies in the purpose and duration. 'vertreten' is used when someone temporarily acts for another person or is present in their place, for example because of illness or vacation. The original person remains important and usually comes back. 'ersetzen' is used when something or someone takes the place of something else because it is missing, broken, unsuitable, or no longer there. This can be permanent. Learners may confuse the words because both have to do with being 'in someone's place'. Memory tip: people often 'vertreten' other people; things are often 'ersetzt' with new things.

Herr Kaya vertritt heute die kranke Kollegin im Meeting.
Mr. Kaya is standing in for his sick colleague in the meeting today.
Wegen des Defekts ersetzt die Firma den alten Drucker.
Because of the defect, the company is replacing the old printer.