The pubspec is written in YAML, which is human readable, but be aware that white space (tabs v spaces) matters. The pubspec file specifies dependencies that the project requires, such as particular packages (and their versions), fonts, or image files .
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Pub is the package manager for the Dart programming language , containing reusable libraries & packages for Flutter, AngularDart, and general Dart programs. So basically pub is the same as npm or any other package manager but it is specific to dart and flutter.
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