This is not intended to be a complete profile of all the East India Company's activities in India. People much smarter than me have written detailed books on the subject, so I see no reason to belabor the point here.
"The East India Company is, or rather was, an anomaly without a parallel in the history of the world. It originated from sub-scriptions, trifling in amount, of a few private individuals. It gradually became a commercial body with gigantic resources, and by the force of unforeseen circumstances assumed the form of a sovereign power, while those by whom its affairs were directed continued, in their individual capacities, to be without power or political influence." — Bentley's Miscellany 43 (1858)
On the very last day of 1600, a group of London businessmen put together the Governor and Company of Merchants of London Trading into the East Indies, a business venture that would eventually become known colloquially as the English East India Company. This peculiar corporation would eventually become one of the governing powers of the world, controlling wide swaths of land that totaled a greater area than the whole of the United Kingdom prior to the Crown taking control in the 1800s. For nearly three hundred years, the East India Company was one of the premier trading corporations in silk, spices, cotton, and indigo from the Indian subcontinent.
The company enjoyed a monopoly until the latter part of the 1600s, when a rival company was formed and began trading in India. The two companies merged in 1708 to create the United Company of Merchants of England trading to the East Indies. The Company was challenged by foreign competitors in the form of the Dutch and the French. These challenges from foreign companies required the East India Company to form its own military and administrative departments, which in essence turned it from a business into an imperial power by itself.
The Company acquired Bengal in 1757, which expanded its territory, and for the next 16 years British policy in India was determined by meetings of the East India Company's shareholders. Parliament passed the Regulating Act of 1773, which reigned in the control the East India Company had over the Crown's colonies in East Asia, and eleven years later they signed the India Act into law.
The India Act of 1784, commonly called Pitt's India Bill, installed a Governor-General and a Board of Control that superseded the authority of the East India Company. This board operated as a collaborative effort between the Directors of the Company and the Crown, as represented by the Board of Control. Six directors sat on the board -- two from the Cabinet and four from the Privy Council.
In 1813, the Company's monopoly and all trading activities were officially halted with the Charter Act. It worked as the government's agency from 1834 until the 1857 India Mutiny. After the mutiny was put down, the Colonial Office took direct control of the Indian colonies. At last, in 1873, the East India Company disbanded.