Static data such as JSON files

Configuration files

Icons and images (JPEG, PNG, GIF, Animated GIF, WebP, Animated WebP, BMP,
and WBMP)

Flutter uses the pubspec.yaml file,
located at the root of your project, to
identify assets required by an app.

flutter

assets

assets/my_icon.png

assets/background.png

The assets subsection specifies files that should be included with the app.
Each asset is identified by an explicit path
relative to the pubspec.yaml file, where the asset file is located.
The order in which the assets are declared does not matter.
The actual directory used (assets in this case) does not matter.
However, while assets can be placed in any app directory, it’s a
best practice to place them in the assets directory.