We review the literature on gold as an investment. We summarize a wide variety of literature, including the papers in this special issue of International Review of Financial Analysis to which this survey acts as an editorial introduction. We begin with a review of how the gold markets operate, including the under researched leasing market; we proceed to examine research on physical gold demand and supply, gold mine economics and move onto analyses of gold as an investment. Additional sections provide context on gold market efficiency, the issue of gold market bubbles, gold's relation to inflation and interest rates, and the very nascent literature on the behavioural aspects of gold.