gratulieren
to congratulate
To express congratulations to someone on a special occasion (e.g., birthday, wedding) or an achievement (e.g., passing an exam).
Ich gratuliere dir herzlich zum Geburtstag!
I warmly congratulate you on your birthday!

to congratulate
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to congratulate
To express congratulations to someone on a special occasion (e.g., birthday, wedding) or an achievement (e.g., passing an exam).
Ich gratuliere dir herzlich zum Geburtstag!
I warmly congratulate you on your birthday!

The verb 'gratulieren' (to congratulate) requires a fixed structure: the person you congratulate is always in the dative, and the occasion is introduced with the preposition 'zu' + dative. The pattern is: jemandem zu etwas gratulieren (to congratulate someone on something).
Wir gratulieren unserer Kollegin zur Beförderung.
We congratulate our colleague on her promotion.
You congratulate someone on positive events and successes. Common occasions are 'zum Geburtstag' (on one's birthday), 'zur Hochzeit' (on one's wedding), 'zur bestandenen Prüfung' (on passing the exam), 'zum neuen Job' (on the new job), or 'zum Jubiläum' (on the anniversary).
Alle haben ihr zur bestandenen Prüfung gratuliert.
Everyone congratulated her on passing the exam.
'Gratulieren' (to congratulate) is the verb that belongs to the noun 'die Gratulation' (congratulation). If you know the verb, you can also easily understand and use the noun.
Er nahm die vielen Gratulationen seiner Freunde dankend an.
He gratefully accepted the many congratulations from his friends.
to wish
'wünschen' and 'gratulieren' can both be used when you say something positive to a person. 'wünschen' is more general: you express a hope, for example for health, luck, or success. 'gratulieren' fits a specific occasion, such as a birthday, wedding, or passing an exam. Learners may confuse the words because when congratulating someone, you often also say good wishes. The simple difference is: you congratulate someone on something that has happened or is being celebrated; you wish someone something good for the present or future.

Herr Yilmaz gratuliert seiner Kollegin in einer E-Mail zum neuen Job.
Mr. Yilmaz congratulates his colleague on her new job in an email.
Die Eltern wünschen ihrer Tochter viel Glück für den ersten Arbeitstag.
The parents wish their daughter lots of luck on her first day at work.