step 1 : Create “assets/images” folder in your project directory

• Create “assets” folder in your project root directory.
• Create “images” folder in your assets folder.

Flutter Assets Images

Note : 

Your “assets” folder will have “images” and many other project assets like “fonts”, “icons”, “animation files” etc.

step 2 : Add images to your “images” folder

• Just drag-n-drop your image inside the “images” folder

Add images to your flutter project

• Image Relative Path : assets/images/bluetruck.png

step 3 : Register your assets folder in pubspec.yaml file

• Open pubspec.yaml file 
• Add assets subsection to the flutter section or uncomment the assets section and add your image relative path.

• Save the pubspec.yaml file and run “flutter pub get command” in terminal.

• If using Android Studio - Save the file and Click Packages get in action ribbon.
• If using VS Code : It automatically runs command on saving pubspec.yaml file.

Flutter pubspec.yaml file

Note : If you have multiple images that you want to include in your project then you can skip the filename.

For Example,

  assets:
    - assets/images/

• This includes all the images inside “images” folder.
• This is helpful when we have many images to be included in our project.
• Say, we have 25 images in our “images folder” so we will not have to register each image filename inside pubspec.yaml file separately.
• Using the above syntax we can include all images in a single line.

To learn more about flutter - Flutter Developer Guide

step 4 : Code Implementation - Use Flutter Image class

Flutter Image Class - Documentation 

Also refer official class documentation with this guide to deeply understand the concept.

Let us start with the simplest way to display images in our flutter app.

Coding - Flutter Sample App Code 

Flutter Image Class