Why civic and political participation is important?

Runs a democracy and keeps it free-- in a democracy people must participate to be a democracy. 

Civic participation is vital to a democracy by the definition of it being a country in which the people's voice is a major part of the government. If people do not use their power to participate then a democracy is at risk of becoming a tyrannical government run by the elite or the military. The freedoms of the people are dependent upon continued participation.