Foreword: I am very much an amateur in astrophotography and the information is my understanding and may be incorrect.
For astrophotography we need to gather multiple photos and when processed together create the final image. I am using a DSLR so the below is written with that in mind.
The following is a brief breakdown of the types:
Lights
Light frames are your standard image captures. The exposure length and ISO will depend on your setup. These make up the bulk of your data.
Bias
Bias frames are supposed to average out the read noise from your camera sensor.
These frames are captured by covering your lens or telescope so no light can get to the sensor. Take a bunch of photos at the shortest exposure possible. Take at least 50-100 photos. These are quick and can be done anytime.
Darks
Like Bias frames these are to calibrate noise caused by heat in the sensor of your camera. Temperature, exposure length and ISO effect the noise generated.