Question 1

What is the difference between volume and open interest?

Accepted Answer

Volume counts how many contracts or shares traded during a period. Open interest counts how many futures or options contracts are still open and have not been closed out yet. Volume measures activity; open interest measures positions that currently exist.

Question 2

What is the bid-ask spread?

Accepted Answer

The bid is the highest price a buyer is currently willing to pay and the ask is the lowest price a seller will accept. The spread is the gap between them. A wider spread means it costs more to enter and exit a position.

Question 3

Do I need all this extra data to read a chart?

Accepted Answer

No. Price and volume are enough to start. The bid, the ask, open interest, and liquidity are extra context that becomes useful as you study specific markets like futures and options, where these numbers explain things price alone cannot.