What is An Angular Theme?

Question
Exactly what even is an Angular theme?
Answer
A theme consists of configurations for the individual
color
andtypography
systems in Angular Material.
Typography
is optional.
Configuration
Create the color configuration by composing colors from color palettes:
Primary palette: colors most widely used across all screens and components.
Accent palette: colors used for the floating action button and interactive elements.
Warn palette: colors used to convey error state.
Foreground palette: colors for text and icons.
Background palette: colors used for element backgrounds.