What is the dew point and how they occur?

The dew point temp is that temperature at which no more vapour can be absorbed in the air and it become saturated and more of the vapour will be condensed into liquid water. It is always less than or equal to the air temperature. So the dew becomes visible which is actually liquid water drops and called dew point.

the dew point is that temp. that makes the water vapor in the air condensate ..it occur when the ambient is cold enough (in the morning time you can see condensate vapor on the car glass)

The dew point is the point of temperature at which the air can no longer "hold" all of the water vapor which is mixed with it, and some of the water vapor must condensed  into liquid water. The dew point is always lower than (or equal to) the air temperature. 

Dew point as has been explained above. Actually Dew occurs when air is saturated with water vapors / droplets which means higher humidity. So air can not absorb more vapors and vapors are condensed back into liquid forming so called Dew Phenomena. 

1. the atmospheric temperature (varying according to pressure and humidity) below which water droplets begin to condense and dew can form.