A newsletter is an example of "grey literature." Newsletters are used by companies to inform their customers about new products, special offers, and other events/issues that may affect them. They can also be used to promote brand awareness and increase sales by informing people about discounts, coupons, and other promotions. The term is also applied to reports published periodically by organizations such as government agencies, universities, and non-profit groups. Companies may use different methods to distribute their newsletters including email, social networking, paper, radio, television, and more. People like receiving information in forms they can read easily. This allows them to decide if the content is something they want to receive or not. Companies need to consider this when deciding what method will be used to distribute their newsletters. These newsletters are useful for companies to keep their customers up to date with changes that may have been made to their website or product line. Customers can sign up to receive these newsletters via email or online form. Some companies may even send regular newsletters out automatically without asking for permission first.