diff --git a/src/marks/area.d.ts b/src/marks/area.d.ts
index 6bf0edb741..24082291ca 100644
--- a/src/marks/area.d.ts
+++ b/src/marks/area.d.ts
@@ -4,30 +4,168 @@ import type {Data, MarkOptions, RenderableMark} from "../mark.js";
 import type {BinOptions, BinReducer} from "../transforms/bin.js";
 import type {StackOptions} from "../transforms/stack.js";
 
+/** Options for the area, areaX, and areaY marks. */
 export interface AreaOptions extends MarkOptions, StackOptions, CurveOptions {
+  /**
+   * The required primary horizontal position channel, representing the area’s
+   * baseline, typically bound to the *x* scale. For areaX, setting this option
+   * disables the implicit stackX transform.
+   */
   x1?: ChannelValueSpec;
+
+  /**
+   * The optional secondary horizontal position channel, representing the area’s
+   * topline, typically bound to the *x* scale; if not specified, **x1** is
+   * used. For areaX, setting this option disables the implicit stackX
+   * transform.
+   */
   x2?: ChannelValueSpec;
+
+  /**
+   * The required primary vertical position channel, representing the area’s
+   * baseline, typically bound to the *y* scale. For areaY, setting this option
+   * disables the implicit stackY transform.
+   */
   y1?: ChannelValueSpec;
+
+  /**
+   * The optional secondary vertical position channel, representing the area’s
+   * topline, typically bound to the *y* scale; if not specified, **y1** is
+   * used. For areaY, setting this option disables the implicit stackY
+   * transform.
+   */
   y2?: ChannelValueSpec;
+
+  /**
+   * The optional ordinal **z** channel, for grouping data into (possibly
+   * stacked) series to be drawn as separate areas. If not specified, it
+   * defaults to **fill** if a channel, or **stroke** if a channel.
+   */
   z?: ChannelValue;
 }
 
+/** Options for the areaX mark. */
 export interface AreaXOptions extends Omit<AreaOptions, "y1" | "y2">, BinOptions {
+  /**
+   * The horizontal position (or length) channel, typically bound to the *x*
+   * scale.
+   *
+   * If neither **x1** nor **x2** is specified, an implicit stackX transform is
+   * applied and **x** defaults to the identity function, assuming that *data* =
+   * [*x₀*, *x₁*, *x₂*, …]. Otherwise, if only one of **x1** or **x2** is
+   * specified, the other defaults to **x**, which defaults to zero.
+   */
   x?: ChannelValueSpec;
+
+  /**
+   * The vertical position channel, typically bound to the *y* scale; defaults
+   * to the zero-based index of the data.
+   *
+   * If an **interval** is specified, **x** values are binned accordingly,
+   * allowing zeroes for empty bins instead of interpolating across gaps. This
+   * is recommended to “regularize” sampled data; for example, if your data
+   * represents timestamped observations and you expect one observation per day,
+   * use *day* as the **interval**.
+   */
   y?: ChannelValueDenseBinSpec;
+
+  /**
+   * How to reduce **x** values when the **y** channel is binned with an
+   * **interval**; defaults to *first*. For example, to create a vertical
+   * density plot (count of *y* values binned every 0.5):
+   *
+   * ```js
+   * Plot.areaX(data, {y: "value", interval: 0.5, reduce: "count"})
+   * ```
+   */
   reduce?: BinReducer;
 }
 
+/** Options for the areaY mark. */
 export interface AreaYOptions extends Omit<AreaOptions, "x1" | "x2">, BinOptions {
+  /**
+   * The horizontal position channel, typically bound to the *x* scale; defaults
+   * to the zero-based index of the data.
+   *
+   * If an **interval** is specified, **x** values are binned accordingly,
+   * allowing zeroes for empty bins instead of interpolating across gaps. This
+   * is recommended to “regularize” sampled data; for example, if your data
+   * represents timestamped observations and you expect one observation per day,
+   * use *day* as the **interval**.
+   */
   x?: ChannelValueDenseBinSpec;
+
+  /**
+   * The vertical position (or length) channel, typically bound to the *y*
+   * scale.
+   *
+   * If neither **y1** nor **y2** is specified, an implicit stackY transform is
+   * applied and **y** defaults to the identity function, assuming that *data* =
+   * [*y₀*, *y₁*, *y₂*, …]. Otherwise, if only one of **y1** or **y2** is
+   * specified, the other defaults to **y**, which defaults to zero.
+   */
   y?: ChannelValueSpec;
+
+  /**
+   * How to reduce **y** values when the **x** channel is binned with an
+   * **interval**; defaults to *first*. For example, for an area chart of the
+   * count of records by month:
+   *
+   * ```js
+   * Plot.areaY(records, {x: "Date", interval: "month", reduce: "count"})
+   * ```
+   */
   reduce?: BinReducer;
 }
 
+/**
+ * Returns a new area with the given *data* and *options*. The area mark is
+ * rarely used directly; it is only needed when the baseline and topline have
+ * neither *x* nor *y* values in common. Use areaY for a horizontal orientation
+ * where the baseline and topline share *x* values, or areaX for a vertical
+ * orientation where the baseline and topline share *y* values.
+ */
 export function area(data?: Data, options?: AreaOptions): Area;
 
+/**
+ * Returns a new vertically-oriented area for the given *data* and *options*,
+ * where the baseline and topline share **y** values, as in a time-series area
+ * chart where time goes up↑.
+ *
+ * ```js
+ * Plot.areaX(aapl, {y: "Date", x: "Close"})
+ * ```
+ *
+ * Variable aesthetic channels are supported: if the **fill** is defined as a
+ * channel, the area will be broken into contiguous overlapping sections when
+ * the fill color changes; the fill color will apply to the interval spanning
+ * the current data point and the following data point. This behavior also
+ * applies to the **fillOpacity**, **stroke**, **strokeOpacity**,
+ * **strokeWidth**, **opacity**, **href**, **title**, and **ariaLabel**
+ * channels. When any of these channels are used, setting an explicit **z**
+ * channel (possibly to null) is strongly recommended.
+ */
 export function areaX(data?: Data, options?: AreaXOptions): Area;
 
+/**
+ * Returns a new horizontall-oriented area for the given *data* and *options*,
+ * where the baseline and topline share **x** values, as in a time-series area
+ * chart where time goes right→.
+ *
+ * ```js
+ * Plot.areaY(aapl, {x: "Date", y: "Close"})
+ * ```
+ *
+ * Variable aesthetic channels are supported: if the **fill** is defined as a
+ * channel, the area will be broken into contiguous overlapping sections when
+ * the fill color changes; the fill color will apply to the interval spanning
+ * the current data point and the following data point. This behavior also
+ * applies to the **fillOpacity**, **stroke**, **strokeOpacity**,
+ * **strokeWidth**, **opacity**, **href**, **title**, and **ariaLabel**
+ * channels. When any of these channels are used, setting an explicit **z**
+ * channel (possibly to null) is strongly recommended.
+ */
 export function areaY(data?: Data, options?: AreaYOptions): Area;
 
+/** The area mark. */
 export class Area extends RenderableMark {}