Please answer a question about the following article about Eton College:

Eton College has links with some private schools in India today, maintained from the days of the British Raj, such as The Doon School and Mayo College. Eton College is also a member of the G20 Schools Group, a collection of college preparatory boarding schools from around the world, including Turkey's Robert College, the United States' Phillips Academy and Phillips Exeter Academy, Australia's Scotch College, Melbourne Grammar School and Launceston Church Grammar School, Singapore's Raffles Institution, and Switzerland's International School of Geneva. Eton has recently fostered[when?] a relationship with the Roxbury Latin School, a traditional all-boys private school in Boston, USA. Former Eton headmaster and provost Sir Eric Anderson shares a close friendship with Roxbury Latin Headmaster emeritus F. Washington Jarvis; Anderson has visited Roxbury Latin on numerous occasions, while Jarvis briefly taught theology at Eton after retiring from his headmaster post at Roxbury Latin. The headmasters' close friendship spawned the Hennessy Scholarship, an annual prize established in 2005 and awarded to a graduating RL senior for a year of study at Eton. Hennessy Scholars generally reside in Wotton house.

What is the G20 School's Group?
a collection of college preparatory boarding schools from around the world