The Big Four are the four largest professional services networks in the world, the global accounting networks Deloitte, Ernst & Young (EY), KPMG, and PricewaterhouseCoopers (PwC). The four are often grouped because they are comparable in size relative to the rest of the market, both in terms of revenue and workforce; they are considered equal in their ability to provide a wide scope of professional services to their clients; and, among those looking to start a career in professional services, particularly accounting, they are considered equally attractive networks to work in, because of the frequency with which these firms engage with Fortune 500 companies.
Jot some points about "Big Four" using given passage as a reference
1. Deloitte, Ernst & Young (EY), KPMG, and PricewaterhouseCoopers are the four largest professional services networks in the world together known as "The Big Four." (PwC).
2. The four are frequently grouped together because they have similar sizes to the rest of the market in terms of personnel and income, and they are viewed equally in terms of their capacity to offer a broad range of professional services to their clients. 
3. Due to the regularity with which these organisations interact with Fortune 500 corporations, they are equally appealing networks to work in among people seeking to launch a career in professional services, particularly accounting.