Package name is your app’s directory and your app’s location on Google Play Store. That’s why each package name should be unique.
Your package name shouldn’t have spacing or special characters. It should have at least one dot(.) When it comes to the package name best practices; usually the form of opposite domain is used. Ex: “com.companyname.appname”
Package name is also an important factor when your potential users are searching for you in the Google Play Store. Please remember that a package name can not be changed once it’s given. Therefore, pay extra attention to your package name.