In plain English
What OHLC means
In a conventional OHLC bar, the vertical line spans from the low to the high. A short tick on the left marks the opening price, and a short tick on the right marks the closing price. Candlesticks contain the same four data points but display the open-to-close section as a body instead of side ticks.
Why it matters
OHLC data is the basic input for many price charts, technical indicators, and backtests. It allows a reader to see more than a closing-price line would show. However, OHLC does not reveal the exact order in which prices were reached inside the period, so it cannot reconstruct every intraperiod movement.
Example
For a daily EUR/USD bar, assume open 1.0900, high 1.0960, low 1.0875, and close 1.0930. The bar spans 1.0875 to 1.0960; its left tick is at 1.0900 and its right tick is at 1.0930. This simplified bar shows the day’s range and net change.
Quick answers
Common questions
Is OHLC the same as a candlestick?+
No. Both summarize the same four prices for a period, but OHLC is usually shown as a bar with side ticks, while a candlestick uses a body and wicks.
Can OHLC data prove an order would have filled?+
Not always. A bar may show that a price traded during a period, but it generally does not provide the sequence, available liquidity, spread, or execution conditions needed to confirm a fill.
Sources