A commercial invoice is a bill for the goods from the seller to the buyer. Commercial invoices are utilized by customs officials to determine the value of the goods in order to assess customs duties and taxes. 

In general there is no standard form for a commercial invoice although they tend to contain many of the following features:

.seller's contact information 
.buyer's contact information 
.consignee's contact information (if it is different from the buyers) 
.invoice date 
.a unique invoice number 
.sales terms (usually in incoterm format) 
.payment terms 
.currency of sale 
.full quantities and description of merchandise (Generally this includes unit price and total price. Product descriptions should be consistent with the buyer's purchase order. Including the Harmonized System commodity codes can be helpful, especially in countries that are WTO members.) 
.certification that the invoice is correct (Standard language is "We certify that this invoice is true and correct."