The purpose of sampling is to provide various types of statistical information of a qualitative or quantitative nature about the whole by examining a few

To sell something now and let the purchaser pay for it later. (source: http://idioms.thefreedictionary.com/sell+on+credit)

A note that is used as proof of the sale or purchase of goods

The exchange of goods, property, or services for an agreed sum of money or credit at a lower price than the normal value.

Number of individuals working for a particular company or linked somehow to it, engaged in commercial work promoting products or services that the company offers

A job that involves selling a company´s products or services as well as being responsible for winning new customers and looking after existing customer accounts.

Compensation, consideration, or fee paid for a license or privilege to use an intellectual property (brand, copyright, patent, process) or a natural resource (fishing, hunting,

Sale of goods to the general public and not to other businesses. (source: http://www.ehow.com/facts_6798176_meaning-retail-trade_.html#ixzz26SFNmuy6)

A business or person that sells goods to the consumer, as opposed to a wholesaler or supplier, who normally sell their goods to another business.

The sale of goods and services from individuals or businesses to the end-user. (source: http://en.wikipedia.org/wiki/Retail )