Corneille, Rouen
Copywriting consists in expressing facts, opinions or ideas and/or in promoting a person, a concept or an organization in writing using words (even if eventually the copy will be "heard" and not read, for example on TV). In spite of the fact that the word "copy" may be applied to any content intended for printing (as in a newspaper, a book, a manual or another printed material), the term "copywriting" is generally restricted to promotional situations, regardless of the target media, be it audiovisual, printed or electronic.
Thus, the purpose of copywriting is to inform the reader, the listener or the viewer and/or to convince him/her, for example to buy a product or a service or to endorse a certain viewpoint.
Copywriting may be involved in direct mail, taglines, jingles, websites, online ads, e-mail and other Internet content, television or radio commercials, press releases, white papers, catalogs, billboards, brochures, postcards, sales letters, and other marketing communications media.
Content writing for websites is also part of the copywriting craft, and may include, among its objectives, the achievement of higher rankings with search engines. This goal is known as "organic" search engine optimization (SEO); this practice involves the strategic placement and repetition of keywords and keyword phrases on websites, while the content still looks written in a natural way.
(From Wikipedia)