what does ^ mean in pubspec.yaml code example

Example 1: pubspec.yaml local package

dependencies:
  your_package:
    path: ../your_package/

Example 2: pubspec.yaml flutter

dependencies:
  url_launcher: ^5.4.0    # Good, any 5.4.x version where x >= 0 works.
  image_picker: '5.4.3'   # Not so good, only version 5.4.3 works.