You can demonstrate your German language level with two different tests.
“DSH” (German Language University Entrance Examination for Foreign Applicants) and
“TestDaF” (Test of German as a Foreign Language).
German is not a prerequisite if you enrol in an international degree programme or a special post-graduate course. Some universities do not ask for proof of German language proficiency if you plan on studying there for only one or two semesters. This rule does not apply everywhere, however. It’s best to inquire directly at the university of your choice about the language requirements for incoming students.
The reunification of families of foreign students is usually only considered if the student is in possession of a residence permit, if the marriage existed at the time of said permit being granted and if the duration of the foreigner's stay in the Federal territory is expected to exceed one year.
Furthermore, the student has to be able to support himself/herself and his/her family without assistance of public funds.
For families to join students in Germany they would have to apply for a visa for family reunification from the competent Germany mission abroad. Details on the documents to be presented with the visa application are often available on the webpage of the competent German mission abroad or directly from the mission itself.
With so many degree programmes to choose from, it’s not so easy to maintain an overview. If you’re having a hard time deciding, there are tests available online which can help you:
TestAS – Test whether you are prepared for university-level study in Germany (free)
Self-assessment – Particularly suited to technical subjects; test your strengths and weaknesses (free)
Please check it here
https://www.daad.de/deutschland/nach-deutschland/voraussetzungen/en/6017-admission-requirements/
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