During means from the beginning to the end of a particular period of time.

• It rained during the night.
• There was not even a whisper during the whole service.

During can also be used to talk about things that happened continuously or several times between the beginning and the end of a period of time.

• I used to visit him during my stay in Boston.
• The baby woke up several times during the night.

During and For

During is used to say when something happens; for is used to say how long it lasts.

• It rained for three hours.
• It rained during the night.
• I was sleeping during the service.
• The service lasted for more than three hours.
• I don't remember the exact date, but it was during the winter.

During and In

We use both during and in to say that something happens inside a particular period of time.

• I woke up during/in the night.
• It rained during/in the week.

We prefer during when we stress that we are talking about the whole of the period. In cannot be used like this.

• There was not even a whisper during the whole service. (NOT … in the whole service.)
• We were on holiday during the whole of May.