In flutter everything is a widget. Widgets are basically components and blocks used to construct the user interface. There are various different kind of widgets available such as Container, Column and Row.
Container widget helps to style and apply some properties to its child widget. Color property can be applied to bring some background color for the container. It is important to have color properties if it is wrap with multiple containers inside one another. It make structure the widgets.
Container widget takes exactly one child widget
It has rich alignments and styling options
Flexible width (Example: child widget available width)