In order to correctly set up your different sales processes, just as for the default lead structure, you have a default client folder structure.
For more information on Client Folders, click here.
You can choose the information you wish to predefine for all your clients when you create a new client folder. You can define Zip Code, VAT Number, or whatever you believe it's important to have as global information for a customer, and not for a specific lead. When needed, you can also export your client folders.