Small scale industries (SSIs) are defined as businesses with less than 150 employees and fixed asset investments of less than 10 million rupees. SSIs are important for employment generation in India as they employ more people per unit of capital compared to large industries. They also promote balanced regional development by dispersing industries across many locations. Some key roles of SSIs include providing employment, being capital light, requiring less skills and imports, mobilizing resources, supporting agriculture and large industries, and contributing to exports and industrial output.