Pre-shipment Inspections

What is PSI (Pre-Shipment Inspection and Certification) goods? How to carry out the goods Pre-Shipment Inspection?What are the purpose and advantages of pre-shipment inspection?What is PSI in trading and shipping?Who is responsible for pre-shipment import inspections?Why is pre dispatch inspection report to buyer asap?Which are content of Pre Shipment Inspection job and Certification (Report)How long does pre-shipment inspect?