What is "old order amish"

Amish \Am"ish\, a. [Written also Omish.] (Eccl. Hist.) Of, pertaining to, or designating, the followers of Jacob Amman, a strict Mennonite of the 17th century, who even proscribed the use of buttons and shaving as ``worldly conformity''. There are several branches of Amish Mennonites in the United States. A branch having particularly strict adherence to the Amish principles are called Old Order Amish

The Old Order Amish are a North American ethno-religious group consisting of some 2000 local churches. There is no formal church organisation to bind them together, but they are linked by common faith, traditions and ancestry. The Amish separated from mainstream Mennonites in 1693, led by Jakob Ammann. The Old Order Amish form by far the largest group of Amish.