Pixel
A small square that makes up a part of an image.
Resolution
The number of pixels in width and height.
PPI and DPI
Pixels per inch and dots per inch respectively.
Colour Depth/Bit Depth
Measurement of the amount of possible colors that can be displayed with the given bits.
RGB Channels
Red, Green, Blue channels used to create colors in pixels.
Metadata
Data about data, including creation and modification dates.