OHLC (Open, High, Low, Close)

Open is the first traded price of the period. High is the highest. Low is the lowest. Close is the last. Every candle, bar, and most indicators are built from these four, or from a subset of them.

The close is the price most indicators use, because it is the price at which the period agreed to finish. The high and low show the excursion, including prices that did not hold. The open matters for gaps and for candles whose body is the story.

On a candle, open and close are the body edges and high and low are the wick tips. On a session, the official open may be an auction price rather than the first print. Know which one your feed uses.

Before trusting a pattern, name the four prices. A "hammer" is a statement about where the close sits inside the high-low range. Without that, the word is only a shape.

Using a close from one feed and a high from another, or forgetting that an adjusted close is not the price that traded that day.

Four numbers compress every trade in the period. A bar can travel to its high and low in either order. OHLC does not say which came first.