You may create an account using Gmail/Github/Facebook account.
Hypi is an App-based account. App is the building block that you will deploy in your application. Know more about App here. Create an app using the Create a new App or + New App button or + button on the left hand column.
Enter the App name that suits the functionality you are going to implement. (Four characters minimum). There is an option to create a new release and API instance automatically.
Click on newly created App. If you choose to automatically create a release and an instance, a release with the name latest will get created under the tab Versions.
An instance with a domain will get created under the API Instances.
An App ID gets generated automatically after the creation of the App. You may see the App's Id under the Settings. You may copy the App ID from here.
