Dow Jones Industrial Average tracks 30 influential corporations in the US.

S&P/ASX 200 tracks blue-chip stocks on the Australian Securities Exchange (ASX).

S&P 500 is another US-based index tracking 500 American blue chips.

FTSE 100 focuses on the top UK companies.

NASDAQ 100 is unique because it only lists the largest non-financial companies in the US. Most of the current listings are tech companies, so the index has become a barometer for the tech industry.

DAX 30 tracks the most significant German companies and is often quoted as a measure of the economic health of continental Europe.

Hang Seng includes the largest companies in Hong Kong.

Nikkei 225 covers Japan's biggest corporations, but it is often cited as an economic measure for the entire Asia-Pacific region.

EURO STOXX 50/600 tracks the biggest companies in the Eurozone, which includes all economies that rely on the Euro currency.

CBOE Volatility Index (VIX) measures the 30-day volatility (degree of price change) in the US stock markets.