An invoice is a document that a seller provides to a buyer, detailing the products or services rendered. It typically includes information such as the seller's and buyer's contact details, a description of the items sold, the quantity, price, and the total amount due. Invoices serve as a formal request for payment and help keep track of sales and purchases. Invoices are essential for businesses as they provide a record of transactions for accounting purposes. They can also include payment terms, such as due dates and accepted payment methods. Proper invoicing helps maintain clear communication between the seller and buyer, ensuring timely payments and accurate financial records.