die Mitternacht
midnight
The point in time at 24:00 or 0:00; the middle of the night.
An Silvester stoßen die meisten Menschen um Mitternacht mit Sekt an.
On New Year's Eve, most people toast with sparkling wine at midnight.

midnight
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midnight
The point in time at 24:00 or 0:00; the middle of the night.
An Silvester stoßen die meisten Menschen um Mitternacht mit Sekt an.
On New Year's Eve, most people toast with sparkling wine at midnight.

The word 'Mitternacht' (midnight) is built simply: it consists of 'Mitte' (middle) and 'Nacht' (night). So it literally refers to the middle of the night.
Um Mitternacht schlagen die Kirchenglocken zwölfmal.
At midnight, the church bells strike twelve times.
To express the exact time, you use the preposition 'um': 'um Mitternacht' (at midnight). For an approximate time, you can say 'gegen Mitternacht' (around midnight / shortly before) or 'nach Mitternacht' (after midnight / shortly after).
Der letzte Zug fährt pünktlich um Mitternacht.
The last train leaves exactly at midnight.
The related adverb 'mitternachts' means 'at night, around midnight'. It describes when something typically happens.
Mitternachts ist die Stadt vollkommen still.
Around midnight, the city is completely quiet.
night
'die Nacht' (night) and 'die Mitternacht' (midnight) can be confused because both belong to the dark hours. But 'die Nacht' is a longer period of time from evening to morning. 'die Mitternacht' is only a specific point in time, namely around 24:00 or 0:00. If you are talking about sleep, darkness, or several hours, 'Nacht' fits. If you mean an exact time or the change to a new day, 'Mitternacht' fits.

Kurz vor Mitternacht sind die letzten Gäste gegangen.
The last guests left shortly before midnight.
Sie hat die ganze Nacht kaum geschlafen.
She barely slept the whole night.