astroturfing

Astroturfing is the practice of masking the sponsors of a message or organization (e.g., political, advertising, religious or public relations) to make it appear as though it originates from and is supported by grassroots participant(s).

It is a practice intended to give the statements or organizations credibility by withholding information about the source's financial connection. The term astroturfing is derived from AstroTurf, a brand of synthetic carpeting designed to resemble natural grass, as a play on the word "grassroots."