In short : a grass-roots action ( a peoples protest) that is paid for and organised by governments or companies.
The definition is: Astroturfing refers to political, advertising or public relations campaigns that are designed to mask the sponsors of the message to give the appearance of coming from a disinterested, grassroots participant.
Other ways of deception of the public:
False Flag operations: Wikipedia.
A Front organisation : Wikipedia.
Creating a Media hype: Agenda-setting-Theory.
Using a pseudonym to support oneself: Sock-puppeteering.
To practice talkback disguised as a member of the public: Talkback.