The morning is the part of each day between the time that people usually wake up and 12 o'clock noon or lunchtime.

If you refer to a particular time in the morning, you mean a time between 12 o'clock midnight and 12 o'clock noon.

If you say that something will happen in the morning, you mean that it will happen during the morning of the following day.

If you say that something happens morning, noon and night, you mean that it happens all the time.