A simple description would be

• Pre-Carriage – The movement that happens BEFORE the container is loaded on the ship
• Carriage – The movement that happens while the container is ON BOARD the ship
• On-Carriage – The movement that happens AFTER the container is discharged from the ship 

Pre-carriage, carriage, and on-carriage are all terms used in the shipping industry to refer to different stages of the transportation of goods.

Pre-carriage refers to the transportation of goods from the place of origin to the port or place of loading, where the goods are loaded onto the main transport vessel such as a ship or a truck. This can include the use of various modes of transportation, such as truck, train, or barge, to transport the goods from the point of origin to the port or place of loading.

Carriage refers to the transportation of goods from the port or place of loading to the port or place of discharge. This is typically the main leg of the transportation journey and involves the use of a shipping vessel or truck.

On-carriage refers to the transportation of goods from the port or place of discharge to the final destination, or the place of delivery. This can include the use of various modes of transportation, such as truck, train, or barge, to transport the goods from the port of discharge to the final destination.

In summary, pre-carriage is the transportation of goods from the place of origin to the port or place of loading, carriage is the transportation of goods from the port or place of loading to the port or place of discharge, and on-carriage is the transportation of goods from the port or place of discharge to the final destination.