the act of selling user experience to customers, managers, co-workers and employers
Selling is offering to exchange something of value for something else. The something of value being offered may be tangible or intangible. The something else, usually money, is most often seen by the seller as being of equal or greater value than that being offered for sale.
On User Experience selling-ux regards selling user experience to customers, managers, co-workers and employers. Questions having the selling-ux tag regards the act of selling User Experience.
Reference: http://en.wikipedia.org/wiki/Selling