Strokes () are the smallest structural units making up written Chinese characters. In the act of writing, a stroke is defined as a movement of a writing instrument on a writing material surface, or the trace left on the surface from a discrete application of the writing implement. The modern sense of discretized strokes first came into being with the clerical script during the Han dynasty. In the regular script that emerged during the Tang dynasty—the most recent major style, highly studied for its aesthetics in East Asian calligraphy—individual strokes are discrete and highly regularized. By contrast, the ancient seal script has line terminals within characters that are often unclear, making them non-trivial to count.

Study and classification of strokes is useful for understanding Chinese character calligraphy, ensuring character legibility, identifying fundamental components of radicals, and implementing support for the writing system on computers.

Evolution The terminals of the individual marks in ancient character forms are often unclear, and it is sometimes nontrivial to count them. The modern motion of discretized strokes did not fully emerge until clerical script:

Purpose The study and classification of strokes is used for: understanding Chinese character calligraphy – the correct method of writing, shape formation and stroke order required for character legibility; understanding stroke changes according to the style that is in use; defining stroke naming and counting conventions; identifying fundamental components of Han radicals; and their use in computing.

Formation When writing Han radicals, a single stroke includes all the motions necessary to produce a given part of a character before lifting the writing instrument from the writing surface; thus, a single stroke may have abrupt changes in direction within the line. For example: (Vertical / ) is classified as a basic stroke because it is a single stroke that forms a line moving in one direction. (Vertical – Horizontal – Vertical / ) is classified as a compound stroke because it is a single stroke that forms a line that includes one or more abrupt changes in direction. This example is a sequence of three basic strokes written without lifting the writing instrument such as the ink brush from the writing surface.

Direction

All strokes have direction. They are unidirectional and start from one entry point. As such, they are usually not written in the reverse direction by native users. Here are some examples:

Types CJK strokes are an attempt to identify and classify all single-stroke components that can be used to write Han radicals. There are some thirty distinct types of strokes recognized in Chinese characters, some of which are compound strokes made from basic strokes. The compound strokes comprise more than one movement of the writing instrument, and many of these have no agreed-upon name.

Basic strokes A basic stroke is a single calligraphic mark moving in one direction across a writing surface. The following table lists a selection of basic strokes divided into two stroke groups: simple and combining. "Simple strokes" (such as Horizontal / Héng and Dot / Diǎn) can be written alone. "Combining strokes" (such as Bend / Zhé and Hook / Gōu) never occur alone, but must be paired with at least one other stroke forming a compound stroke. Thus, they are not in themselves individual strokes.

+ Table of basic strokesEnglishName in PRCName in ROCName in JapanName in VietnamCJKstrokeMeaning ofChinese name(Japanese name,if different)AdditionaldescriptionSimple strokesDotDiǎn, Diǎn, Ten, Chấm 枕"Dot"Tiny dash, speck.HorizontalHéng, Héng, Yoko, Sổ ngang 𬃈昂"Horizontal"Rightward stroke.VerticalShù, Shù, Tate, Sổ dọc 𬃈𫆡"Vertical"Downward stroke.Upward horizontalTí, Tiāo, Hane, Hất 迄"Rise"("Jump")Flick up and rightwards.PressNà, Nà, (Migi) Harai, Mác 莫"Press down"("(Right) Sweep")Falling rightwards (fattening at the bottom).ThrowPiě, Piě, (Hidari) Harai, Phẩy 𢵪"Throw away"("(Left) Sweep")Falling leftwards (with slight curve).Combining strokesBendZhé, Zhé, Ore, Gập 岋"Bend, fold"Indicates change in stroke direction, usually 90° turn, going down or going right only.HookGōu, Gōu, Kagi, Móc 鈢"Hook"Appended to other strokes, suddenly sharp turning before crash stopping.Clockwise curveWān, Wān, (Hidari) Sori, Cong 𢏣"Curve"Tapering curved line, usually concave left (convex outward right).Anticlockwise curveWān, ; Xié, Qū, (Migi) Sori, Nghiêng 迎㇄; "(Right) curve"; "Slant"Curved line, usually concave right (convex outward left). Note, the basic stroke Diǎn "Dot" is rarely a real dot. Instead it usually takes the shape of a very small line pointing in one of several directions, and may be long enough to be confused with other strokes.

Compound strokes

A compound stroke (also called a complex stroke) is produced when two or more basic strokes are combined in a single stroke written without lifting the writing instrument from the writing surface. The character (pinyin: ) "eternity", described in more detail in , demonstrates one of these compound strokes. The centre line is a compound stroke that combines three stroke shapes in a single stroke.

Basics for making compound strokes In most cases, concatenating basic strokes together form a compound stroke. For example, Vertical / Shù combined with Hook / Gōu produce (Vertical–Hook / Shù Gōu). A stroke naming convention sums the names of the basic strokes, in the writing order.

An exception to this applies when a stroke makes a strictly right-angle turn in the Simplified Chinese names. Horizontal (Héng) and Vertical (Shù) strokes are identified only once when they appear as the first stroke of a compound; any single stroke with successive 90° turns down or to the right are indicated by a Bend 折 (pinyin: zhé). For example, an initial Shù followed by an abrupt turn right produces (Shù Zhé). In the same way, an initial Shù followed by an abrupt turn right followed by a second turn down produces (Shù Zhé Zhé). However, their inherited names are "Vertical–Horizontal" and "Vertical–Horizontal–Vertical". We need not to use "Bend" in the inherited names.

Nearly all complex strokes can be named using this scheme.

Nomenclature Organization systems used to describe and differentiate strokes may include the use of roman letters, Chinese characters, numbers, or a combination of these devices. Two methods of organizing CJK strokes are by:

Classification schemes that describe strokes by a naming convention or by conformity to a taxonomy; and Categorization schemes that differentiate strokes by numeric or topical grouping.

In classification schemes, stroke forms are described, assigned a representative character or letterform, and may be arranged in a hierarchy. In categorization schemes, stroke forms are differentiated, sorted and grouped into like categories; categories may be topical, or assigned by a numeric or alpha-numeric nominal number according to a designed numbering scheme.

Pinyin naming convention in Unicode standard A naming convention is a classification scheme where a controlled vocabulary is used systematically to describe the characteristics of an item. The naming convention for a CJK stroke is derived from the path mark left by the writing instrument. In this instance, the first letter of each stroke component - transliterated with pinyin pronunciation - are concatenated to form a stroke name with the sequence of letters indicating the basic strokes or stroke components used to create the CJK stroke. This system is used in the Unicode standard when encoding CJK stroke characters. In a basic stroke example, H represents the stroke named (); in a compound example, represents ().

While no consensus exists, there are up to 12 distinct basic strokes that are identified by a unique radical.

+ Letters commonly used in CJK stroke naming conventions (12 items); Letter B D G H N P Q S T W X Z Stroke directionSimp./Trad.//()///PinyinBiǎnDiǎnGōuHéngNàPiěQuānShùTíWānXiéZhéMeaning"Flat""Dot""Hook""Horizontal""Right-falling""Left-falling""Circle""Vertical""Rising""Curved""Slant""Bent"

There are many CJK compound strokes, however there is no consensus for sequence letter naming of compound strokes using the basic strokes. The following table demonstrates one of the CJK stroke naming convention:

+ Selected named CJK basic and compound strokesStrokeName in PRCAbbrFull NameDictionary meaning and NoteExample charactersEncoding横HHéng yī, "cardinal number one", "alone" (Radical 1 一).二 三 丁 丞 丈 世 不 上 十 卅 七U+31D0 (㇐)提TTí 冰 淋 病 孑 治 冶 冽 暴 氾 录 地 虫U+31C0 (㇀)横钩HGHéng Gōu wān, ya, zhé (折) turning stroke / to break (Radical: Variant form of 乙 yǐ).疋 了 危 予 矛 子 字 令 疏 写 冖U+31D6 (㇖)横撇HPHéng Piě 又 水 夕 径 炙 双 叒 今U+31C7 (㇇)横折HZHéng Zhé 口 囗 己 田 品 吕 申 甲 圆 巪U+31D5 (㇕)横折钩HZGHéng Zhé Gōu(Radical: Variant form of 乙 yǐ).羽 习 包 勻 葡 用 青 甫 勺 月 也 乜U+31C6 (㇆)横折提HZTHéng Zhé Tí 讠 计 鳩U+31CA (㇊)横折折HZZHéng Zhé Zhé 凹U+31C5 (㇅)横折弯HZWHéng Zhé Wān 殳 投 朵U+31CD (㇍)横折弯钩HZWGHéng Zhé Wān GōuUnofficial name "HWG" is used by Hugo Lopez to refer to both HZWG and HXG.九 几 丸 杂 U+31C8 (㇈)横斜钩HXGHéng Xié GōuThis stroke was merged into stroke HZWG in Unicode.,; but later disunified.飞 风 瘋 凬 虱 迅 气U+31E4 (㇤)横斜弯钩(横折弯钩)HXWG(HZWG)Héng Xié Wān Gōu(Héng Zhé Wān Gōu) yǐ, niè, "the second of the ten heavenly stems", "second"; zhé (折) turning stroke / to break (Radical 5 乙).氹 乞 乤 艺U+31E0 (㇠)横折折折HZZZHéng Zhé Zhé Zhé 凸U+31CE (㇎)横折折撇HZZPHéng Zhé Zhé Piě 建 及U+31CB (㇋)横撇弯钩HPWGHéng Piě Wān Gōu 阝 队 邮U+31CC (㇌)横折折折钩HZZZGHéng Zhé Zhé Zhé Gōu nǎi, archaic form of "then", "really, indeed", "namely", "you, your".乃 孕 仍U+31E1 (㇡)竖SShù gě, gǔn, "vertical line" (Radical 2 丨).丩 中 串 讧 乍 上 五 丑U+31D1 (㇑)竖钩SGShù Gōu jué, "a vertical line with a hook" (Radical 6 亅).爭 事 求 水U+31DA (㇚)竖提STShù Tí 以 比 切 卯 食 良 艮 很 狠 鄉 民U+31D9 (㇙)竖折SZShù Zhé 断 陋 继 山 互 彙 牙 乐 东U+31D7 (㇗)竖弯SWShù Wān 區 亡 妄 四U+31C4 (㇄)竖弯左SWZShù Wān Zuǒ 肅 嘯 蕭 簫U+31D8 (㇘)竖弯钩SWGShù Wān Gōu yǐn, "hidden", "mysterious", "small", usually read as / yǐn (Radical: Variant form of 乙 yǐ).乱 己 已 巳U+31DF (㇟)竖折折SZZShù Zhé Zhé 亞 鼎 卐 吳U+31DE (㇞)竖折撇SZPShù Zhé PiěThis stroke was merged into stroke SZZ in Unicode., but later disunified.专 𧦮 𤓷 𤦡U+31E5 (㇥)竖折弯钩(竖折折钩)SZWG(SZZG)Shù Zhé Wān Gōu(Shù Zhé Zhé Gōu) 亏 强 弓 丏 丐 与 马 鸟 丂 号U+31C9 (㇉)撇PPiě usually read as 撇 piě, "line", "slash" (Radical 4 丿).乂 爻 禾 毛 乏 乖 釆 衣 八 行U+31D2 (㇒)竖撇SPShù Piě 乃 月 用 齊 几 人 班 大U+31D3 (㇓)撇钩PGPiě Gōu 乄U+31E2 (㇢)撇折PZPiě Zhé 弘 玄 公 厶 翁U+31DC (㇜)撇点PDPiě Diǎn quǎn, a little drain between fields, usually read as quǎn (Radical 47 巛).女 巛 巡 獵 災 甾U+31DB (㇛)点DDiǎn zhǔ, "dot", usually read as 點 / 点 diǎn (Radical 3 丶).丸 叉 义 永 冰 凡 丹 主 求 火 刃U+31D4 (㇔)捺NNà㇏ usually read as 捺 nà.大 人 天 入 走 边 廷 尺U+31CF (㇏)提捺TNTí Nà(1) fú, "stretch". (2) yí, "to move" (archaic).尐 之 道 八 入 廻U+31DD (㇝)斜钩XGXié Gōu 戈 弋 戰 我U+31C2 (㇂)扁斜钩BXGBiǎn Xié Gōu 心 必 沁 惢 蕊U+31C3 (㇃)弯钩WGWān Gōu 狐 狱 豹 家 啄 嶽 貓 家 逐U+31C1 (㇁)圈QQuān líng, "zero"; also read as quān, "circle". Rare.〇 㔔 㪳 㫈U+31E3 (㇣)

Besides, some strokes have been unified or abandoned in Unicode:

+ CJK basic and compound strokes which have been unified or abandonedStrokeName in PRCAbbrFull NameNoteExample characters横撇弯HPWHéng Piě WānIt only appears in Regular script, can be merged into stroke HPHP in Song typeface.辶 过 边竖折折弯钩SZZWGShù Zhé Zhé Wān GōuThis stroke has been merged into stroke SZZG in Unicode.弓 丐弯WWān It never occurs alone, only appears inside compound strokes.辶 豕 𢀓弯钩WGWān Gōu It never occurs alone, only appears inside compound strokes.乙点捺DNDiǎn NàThis stroke has been merged into stroke N in Unicode.內 全 廴平捺PNPíng NàThis stroke has been merged into stroke N in Unicode.是 走 廴提平捺TPNTí Píng NàThis stroke has been merged into stroke TN in Unicode.辶 之 辷