Thematic investing
Over the long-term (decades, rather than weeks and months), companies and industries are shaped by the world in which they operate.
Thematic investment is part crystal ball gazing and part commonsense. A major theme dominating world stock markets today is the price of oil.
A thematic investor may take a view on the world oil price and invest accordingly. Or more likely he or she will look beyond oil - which is a finite resource - and invest in companies specialising in alternative energy.
Sometimes it isn't the large global themes that drive the market.
Retailers are swayed by consumer confidence and banks ride the interest rate cycle. Investing in either means taking a view on a single issue.
And there left-field themes such as ethical investments.