I'm obsessed with filming. 
Cinematograpy is awesome!  It is the science or art of motion-picture photography by recording light or other electromagnetic radiation
How do cinematographers record light? 
They typically do it electronically by means of an image sensor, or chemically by means of a light-sensitive material such as film stock.
Where does the word cinematography come from?
The actual word "cinematography" was created from the Greek words "kinema", meaning "movement, motion" and "graphein" which means "to record"
Why were films only made in black & white during the early days?
I really don't know!  But it is certainly interesting that cinematography is used in many fields of science and also for entertainment purposes!
Does modern cinematography still use film stock?
I'm not sure if it is still used today, but I do know that images on film stock  are played back at a rapid speed and projected onto a screen