OHLC (OHLC)

OHLC is the standard data format behind most price charts. The Open is the first price traded when a session begins. The High and Low are the extreme peaks and valleys reached during that session. The Close is the final traded price when the session ends. Together, these four numbers compress every trade in a given period — a minute, an hour, a day, or a week — into one compact summary. You can explore how these sessions work in the guide on how market quotes work.

OHLC data is the raw material for candlestick charts and bar charts. Each visual bar or candle is simply a drawing of those four values. The High and Low define the full vertical range. The Open and Close define a narrower inner range that shows where prices settled relative to where they started. That inner range is what tells traders whether buyers or sellers dominated the session.

A common confusion is assuming the Close is the most important of the four. In many analytical tools it receives the most weight, but the High and Low are just as informative — they reveal the extremes that the market tested and rejected. Another misread: on continuously traded markets like crypto, the "open" of one period is simply the close of the previous one, so there are no overnight gaps the way there are in stock markets.