The g-index is introduced as an improvement of the h-index to measure the global citation performance of a set of articles. If the articles are ranked in decreasing order of citations, the g-index is the largest number such that the top g articles together have at least g² citations. It is proven that the g-index always exists and is unique, with g ≥ h. The general theory of the g-index is based on Lotka's law, leading to the formula g = ((α-1)/(α-2))^( (α-1)/α ) * T^(1/α), where α is the Lotkaian exponent and T is the total number of sources. The g-index better accounts for the citation scores of top articles, providing a more accurate distinction between scientists. It is shown that the g-index outperforms the h-index in capturing overall citation performance. The g-index is applied to the Price medallists, demonstrating its superiority in reflecting visibility and lifetime achievement. The paper concludes with open questions regarding further exploration of the g-index and its application in different fields.The g-index is introduced as an improvement of the h-index to measure the global citation performance of a set of articles. If the articles are ranked in decreasing order of citations, the g-index is the largest number such that the top g articles together have at least g² citations. It is proven that the g-index always exists and is unique, with g ≥ h. The general theory of the g-index is based on Lotka's law, leading to the formula g = ((α-1)/(α-2))^( (α-1)/α ) * T^(1/α), where α is the Lotkaian exponent and T is the total number of sources. The g-index better accounts for the citation scores of top articles, providing a more accurate distinction between scientists. It is shown that the g-index outperforms the h-index in capturing overall citation performance. The g-index is applied to the Price medallists, demonstrating its superiority in reflecting visibility and lifetime achievement. The paper concludes with open questions regarding further exploration of the g-index and its application in different fields.