Shipping labels display the key information for a carrier to transport a package from their start destination (your warehouse) to its end destination (the customer’s hands).
The key information includes: postal code, country, tracking number, date, package quantity as well as the weight, address, validation, and ship street, city and state (area). Shipping labels can also specify the contents, particularly if they’re for international shipments.
Labels also include information relating to the method of shipping (e.g. Express, Standard, etc.) for the carrier to ensure the service that was paid for is provided.
Each label is unique and you cannot reuse old labels. A new label must be created for each delivery.