Trump said he would of course invite Putin to the meeting, I think he is an important factor.
The group of seven was founded in the 1970s. Its members include the United States, the United Kingdom, Canada, France, Germany, Italy and Japan. After Russia joined in 1997, it became the group of eight (G8). When the Ukraine crisis broke out in 2014, seven countries refused to attend the G8 summit originally scheduled to be held in Russia, and instead held the G7 summit.