He started by telling us about pixels.
A picture element is a physical point in a raster image or the smallest addressable element in a display device. (Devices such as computer screens and big screen televisions.)
It is the smallest controllable element of a picture represented on the screen.
Pixel comes from the combination of the word picture (pix) and element. It is a portmanteau.
Although pixel is a fairly new word, pix is not. The word pix appeared in Variety magazine headlines in 1932, as an abbreviation for the word pictures. This was in reference to movies.
The first appearance of the word pixel was in 1965. Frederic C. Billingsley of the Jet Propulsion Lab used it to describe the picture elements of video images from space probes to both the moon and Mars.
Billingsley did not coin the term. He got the word pixel from Keith E. McFarland, at the Link Division of General Precision in Palo Alto. At the time, (1963) McFarland does not know where the word originated.