In any country, cargo must be cleared with customs authorities before release.
When cargo is cleared, customs usually levies a certain amount of tax, duty on the products that are imported.
In some cases, the importer may not have the necessary funds to pay the duty in full and clear the goods. This means the cargo could be stuck in the container which could then incur demurrage and port storage if not cleared in time.
In cases like that, the importer can clear the goods under bond which effectively means they enter into an agreement with customs that they will pay duties and taxes in a timely manner.