Here is a comprehensive summary of the Wikipedia article on the BMW Championship:

The BMW Championship is a professional golf tournament that serves as the penultimate event in the PGA Tour's FedEx Cup playoffs, having been introduced in 2007 as the successor to the historic Western Open, which dates back to 1899 and was once considered a major championship. Run by the Western Golf Association, it holds the distinction of being the longest-running regular PGA Tour event outside the four majors, and it was honored as the PGA Tour's Tournament of the Year in 2012, 2013, and 2014. The tournament uses a limited format, open to the top 50 FedEx Cup points leaders (reduced from 70 after 2022), features no 36-hole cut, and the top 30 finishers advance to the Tour Championship to decide the FedEx Cup champion. The first four editions were held at Cog Hill Golf & Country Club, but since 2011 the event has moved to a different course each year, traveling through the Midwest and occasionally the Mid-Atlantic and Colorado, though the Chicago metropolitan area remains its most frequent host with ten stagings. This combination of deep historical roots and modern playoff intensity makes it a unique and prestigious stop on the golf calendar.