For their opponents, it is a shadowy organisation with links in the media and business whose spiritual leader Fethullah Gulen has much unelected and unaccountable influence in the country.
Now the movement and Gulen are accused of launching Friday's military coup together, acting under the name the "Fethullahci Terror Organisation (FETO)", accusations they deny strongly.
The movement's leader is a Sunni Muslim, part of the Hanafi tradition of Islamic jurisprudence and is believed to have been influenced by the ideas of one of the most significant Muslim theologians of the modern world, Said Nursi.
Gulen promotes a tolerant and moderate Sufi Islam, of which Hizmet's supporters are also affiliates, but he himself is a reclusive figure.
He has been active since the 60s and 70s but now lives in self-imposed exile in Pennsylvania in the United States.
Hizmet promotes peace and harmony through hard work and altruism, supporters say.
Their charity efforts and work on education spreads as far as the United States where they have over 100 charter schools, the largest network within the country.
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Hizmet-affiliated schools can also be found in Africa including Kenya and as far as Pakistan and Kazakhstan, usually funded by wealthy Turkish businessmen.
The movement encourages followers to work in the civil service and be useful members of society through charity or employment.
It is not known exactly how many individuals are part of the movement but some believe it could be millions across the world.
There are many think-tanks, businesses, media organisations linked to the movement worldwide including the Journalist and Writers Foundation based in Istanbul and the Rumi Forum in Washington.
Purge of followers
Followers of the movement have had senior positions within Turkey's civil service, media and business, though that has declined since the authorities' purge of those accused of Hizmet links.
Media organisations in Turkey linked to Hizmet have come under great scrutiny and attack.
In March, the headquarters of Zaman daily newspaper was seized by authorities and state administrators put in charge of the parent company, Feza.
That incident came five months after Koza-Ipek media group, parent company of Bugun TV broadcaster -- was ordered to be seized by a court ruling.
After Friday's coup thousands more individuals accused of Hizmet links have been detained and Erdogan suggested more were to come, saying the "virus" that spread within state bodies must be cleaned.