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A Candlestick Chart (Japanese Candlestick Chart) encodes four price dimensions per time period — open, high, low, and close (OHLC) — into a single visual glyph called a "candle." The rectangular real body spans from open to close price; its height encodes the strength of the session's price movement and its colour encodes direction. In this chart, walnut (dark) bodies indicate bullish sessions where price closed above the open; red bodies indicate bearish sessions where the close fell below the open. The thin vertical lines extending above and below the body are called wicks or shadows — they record the full price range explored during the session, including any moves that were subsequently reversed. No other single chart type can convey all four OHLC values simultaneously with this economy of ink.
This chart displays daily OHLC price data across a simulated multi-month trading period, structured to demonstrate the full vocabulary of candlestick reading. Watch for marubozu candles — bodies with minimal or no wicks, indicating sessions of exceptional directional conviction where price moved cleanly in one direction from open to close. Doji candles show sessions where open and close prices were nearly identical, creating a cross-shaped mark that signals market indecision or equilibrium between buyers and sellers. Enable the pattern annotations toggle to label hammer formations and engulfing sequences in the data. Use scroll-to-zoom and drag-to-pan to examine individual sessions in detail; the stats bar at the top updates live with exact OHLC values as you hover each candle.
A Candlestick Chart encodes four price dimensions per time period — open, high, low, close (OHLC) — into a single glyph. The real body spans the open-to-close range and is the primary signal: its height encodes price conviction, its colour encodes direction. The wicks (upper and lower shadows) extend to the session's extremes, encoding the full range of price exploration.
This is a glyph chart — a composite mark that packs four quantitative values into one symbol. It exploits position-along-axis (the most accurate perceptual channel) for the body, and length-from-reference for the wicks. The colour encoding is redundant with the body position: walnut means close > open, red means close < open.
The message is about market psychology across sessions — not a single price level, not a trend line, not a distribution. The viewer needs to see conviction (body height), direction (colour), and range exploration (wick length) simultaneously. No single-dimension chart can deliver all four OHLC values. A line chart collapses to close price only, discarding 75% of the available information. A simple OHLC bar chart encodes the same data but is perceptually harder to parse at density.
The candlestick's cultural familiarity in financial contexts is also an asset: experienced traders read candle patterns instantly. The chart meets the audience where they are.
A line chart on closing price — the most common alternative — discards open, high, and low entirely. The viewer loses all information about intra-session volatility, gap openings, and the relationship between opening conviction and closing outcome. A session that opened high, sold off dramatically, but recovered to close flat appears identical to a calm session that never moved.
A Box Plot — visually similar — encodes statistical distribution (quartiles, median) across many observations. A candlestick encodes four specific price events within one time period. Confusing them is a category error: the box plot answers "how is this value distributed?", the candlestick answers "what happened during this session?".
FT Visual Vocabulary — Change Over Time (specialist glyph variant). The candlestick is a composite glyph in the Change Over Time category: it plots four time-indexed values as a single symbol rather than four separate series. Abela quadrant: Relationship (within-period OHLC relationships) nested inside Change Over Time. Tufte principle applied: maximum data density per unit of ink — four quantitative values encoded in one glyph, with colour as redundant encoding for the primary directional signal. The one design decision worth knowing: body colour uses palette roles (walnut for bullish, blood-red for bearish) rather than conventional green/red, preserving the Humanitarians AI brand identity while maintaining the categorical signal through both colour and body-position direction.