A sales invoice is a receipt of the purchase of either goods or services by an individual from a certain shop or store. It shows a breakdown of all the purchases made by the individual along with their individual prices. The date of purchase is also mentioned on the receipt. Any special instructions given by the buyer is also written in the sales invoice. The sales invoice also declares any terms and conditions on which goods are sold. The sales invoice also mentions the name of the store along with their contact number for future references.