G7 Bonds refer to bonds that are issued by the governments of the following seven countries: United States, Canada, France, Italy, United Kingdom, Germany and Japan. These bonds can be purchased on an individual bond basis or in the form of a group of bonds or "bond fund"- some are available in mutual funds for retail investors.
In 2008 and early 2009, G7 bonds became very popular for their conservative steady nature as investors turned to the U.S. Treasury and other government-backed bonds. G7 bonds are bonds issued by the governments of what are considered the seven largest stable governments currently marketable to investors. Investors seek these bonds for their portfolios when they want income-producing investments with low risk and piece of mind.
As an alternative to G7 government bonds, if you're considering bonds from less developed countries, check out An Introduction To Emerging Market Bonds.
This question was answered by Steven Merkel.