Organisation culture is a set of values, norms and practices prevalent across the echelons of a company. Its like the norms of a family or a society, which is omnipresent and impacts your conduct, interactions and your decision making.
A company’s culture is set in an implicit manner by its Founders. The Founder’s values are the company’s values. As the company grows, more people with different value systems and cultural background join. At this point, The founder or the CEO can take the decision to modify its culture considering the new additions or impose the founders culture.