DPI: DPI stands for Dots per Inch, it is a measure of spatial printing and video dot density, in particular the number of
individual dots that can be placed in a line within the span of 1 inch (2.54 cm).
PPI: PPI stands for Pixels per inch, it is the measure of pixels per one inch or 2.54 cm of a picture, the higher the pixel ratio, the higher the resolution will be.
Metadata: is data that describes other data. Meta is a prefix that in most information technology usages means "an underlying definition or description." Metadata summarizes basic information about data, which can make finding and working with particular instances of data easier.