Short answers, pulled from the story.
The G8 comprised France, Germany, Italy, Japan, the United Kingdom, the United States, Russia, and Canada. Russia was added to the forum in 1997, and the following year the group officially became known as the Group of Eight. The European Union participated since the 1980s as a nonenumerated member that originally could not host or chair summits.
Russia was suspended from the G8 on the 24th of March 2014, following its annexation of Crimea. The other G8 members cancelled the planned Sochi summit and suspended Russia's membership indefinitely, stopping short of permanent expulsion. Russia subsequently announced its permanent withdrawal from the forum in January 2017.
Russia began attending G7 meetings informally after the 1994 Naples summit, in an arrangement nicknamed the Political 8, or P8. UK Prime Minister Tony Blair and US President Bill Clinton invited Boris Yeltsin, who attended first as a guest observer and later as a full participant. Russia formally joined the group in 1998.
At the 2009 L'Aquila summit, G8 members pledged $22 billion to address the global food supply. By 2015-93 percent of those funds had been disbursed to projects covering sustainable agriculture and emergency food aid. In 2012, President Barack Obama also asked G8 leaders to adopt the New Alliance for Food Security and Nutrition initiative.
The G20 replaced the G8 as the main economic council of wealthy nations. G20 leaders formally announced this at their September 2009 Pittsburgh summit. The G8 continued as a forum for like-minded high-income countries but had ceded its central economic coordination role to the larger body.
The G8 Youth Summit, later renamed the Y8, gathered young leaders from G8 nations and the European Union between 2006 and 2013. Participants aged 18 to 35 produced a consensus document called the Final Communique, which was presented to G8 heads of government. The first summit to use the Y8 name took place in May 2012 in Puebla, Mexico.