- Gold is a safe haven. When the world is anxious, money runs to gold. It pays no interest, so when interest rates are high, people like it less.
- Oil is a seesaw of supply and demand. Producing countries agree to pump less — the price goes up. The economy slows, factories need less fuel — the price goes down. It moves sharply.
- Indices are the whole market in one number: the S&P 500 and Nasdaq in the US, the DAX in Germany. One company can crash and the index will barely notice. That's why indices swing more calmly than individual stocks.
You can't buy an index on its own — it's a number. People trade it with a contract for difference (CFD) or buy a fund that copies it. More on funds in the last course.