What is a Cossack and what were there known for?

A Cossack is a member of a group of Orthodox Slavic people who have their own culture and traditions and lived mostly in Ukraine and southern Russia since at least the 16th century. Cossacks are known for their characteristic style of horse-riding and their martial abilities, and are particularly renowned for their military skills, which were developed during the battles and wars they often fought against invading forces. Besides their military prowess, they also had a strong sense of national loyalty and local autonomy, resisting foreign forces and rulers throughout history. They were also known for their strong economic and social impact, as they had their own economy and their own customs, beliefs, and traditions.