Kaomoji was invented in the 1980s as a way of portraying facial expressions using text characters in Japan. It was independent of the emoticon movement started by Scott Fahlman in the United States in the same decade. Kaomojis are most commonly used as emoticons or emojis in Japan.

Users from Japan popularized a style of emoticons (顔文字, [[[wikt:顔文字|kaomoji]]] Error: {{Transliteration}}: transliteration text not Latin script (pos 8) (help), lit. 'face characters'^[1]) that can be understood without tilting one's head.^[2] This style arose on ASCII NET, an early Japanese online service, in the 1980s.^[3][4] They often include Japanese typography in addition to ASCII characters,^[2] and in contrast to Western-style emoticons, tend to emphasize the eyes, rather than the mouth.^[5]

Wakabayashi Yasushi is credited with inventing the original kaomoji (^_^) in 1986.^[5] Similar-looking emoticons were used on the Byte Information Exchange (BIX) around the same time.^[6] Whereas Western emoticons were first used by US computer scientists, kaomoji were most commonly used by young girls and fans of Japanese comics (manga). Linguist Ilaria Moschini suggests this is partly due to the kawaii ('cuteness') aesthetic of kaomoji.^[5] These emoticons are usually found in a format similar to (*_*). The asterisks indicate the eyes; the central character, commonly an underscore, the mouth; and the parentheses, the outline of the face.

Different emotions can be expressed by changing the character representing the eyes: for example, "T" can be used to express crying or sadness: (T_T). T_T may also be used to mean "unimpressed". The emphasis on the eyes in this style is reflected in the common usage of emoticons that use only the eyes, e.g. ^^. Looks of stress are represented by the likes of (x_x), while (-_-;) is a generic emoticon for nervousness, the semicolon representing an anxiety-induced sweat drop (discussed further below). /// can indicate embarrassment by symbolizing blushing, resembling the lines drawn on cheeks in manga.^[7] Characters like hyphens or periods can replace the underscore; the period is often used for a smaller, "cuter" mouth, or to represent a nose, e.g. (^.^). Alternatively, the mouth/nose can be left out entirely, e.g. (^^).

Parentheses are sometimes replaced with braces or square brackets, e.g. {^_^} or [o_0]. Many times, the parentheses are left out completely, e.g. ^^, ^-^, >.<, o_O, O.O, e_e, or e.e. A quotation mark ", apostrophe ', or semicolon ; can be added to the emoticon to imply apprehension or embarrassment, in the same way that a sweat drop is used in manga and anime. Anime forum posters at sometime in the 2000s began using the Japanese style kaomoji.^[8] As a result, Americans and westerners began to use various kaomoji, often referring to them as emoticons.^[9] Some of the designs did differ, mainly due to the differences between western and Japanese keyboards.^[10]

Communication software allowing the use of Shift JIS encoded characters rather than just ASCII allowed for the development of more kaomoji using the extended character set including hiragana, katakana, kanji, symbols, Greek and Cyrillic alphabet, such as (^ム^), (`Д´) or (益).

Modern communication software generally utilizes Unicode, which allows for the incorporation of characters from other languages and a variety of symbols into the kaomoji, as in (◕‿◕✿) (❤ω❤) (づ ◕‿◕ )づ (▰˘◡˘▰).^[11]

Further variations can be produced using Unicode combining characters, as in ٩(͡๏̯͡๏)۶ (٩(͡๏̯͡๏)۶) or ᶘᵒᴥᵒᶅ (ᶘᵒᴥᵒᶅ).

English-language anime forums adopted those Japanese-style emoticons that could be used with the standard ASCII characters available on Western keyboards. Because of this, they are often called "anime style" emoticons in English. They have since seen use in more mainstream venues, including online gaming, instant-messaging, and non-anime-related discussion forums. Emoticons such as <( ^.^ )>, <(^_^<), <(o_o<), <( -'.'- )>, <('.'-^), or (>';..;')> which include the parentheses, mouth or nose, and arms (especially those represented by the inequality signs < or >) also are often referred to as "Kirbys" in reference to their likeness to Nintendo's video game character Kirby. The parentheses are sometimes dropped when used in the English language context, and the underscore of the mouth may be extended as an intensifier for the emoticon in question, e.g. ^_________^ for very happy. The emoticon t(-_-t) uses the Eastern style, but incorporates a depiction of the Western "middle-finger flick-off" using a "t" as the arm, hand, and finger. Using a lateral click letter for the nose such as in ( ͡° ͜ʖ ͡°) is believed to originate from the Finnish image-based message board Ylilauta, and is called a "Lenny face".^[12] Another apparently Western invention is the use of emoticons like *,..,* or `;..;´ to indicate vampires or other mythical beasts with fangs.

Exposure to both Western and Japanese style emoticons or kaomoji through blogs, instant messaging, and forums featuring a blend of Western and Japanese pop culture has given rise to many emoticons that have an upright viewing format. The parentheses are often dropped, and these emoticons typically only use alphanumeric characters and the most commonly used English punctuation marks. Emoticons such as -O-, -3-, -w-, '_', ;_;, T_T, :>, and .V. are used to convey mixed emotions that are more difficult to convey with traditional emoticons. Characters are sometimes added to emoticons to convey an anime- or manga-styled sweat drop, for example ^_^', !>_<!, <@>_____<@>;;, ;O;, and *u*. The equals sign can also be used for closed, anime-looking eyes, for example =0=, =3=, =w=, =A=, and =7=. The uwu face (and its variations UwU and OwO), is an emoticon of Japanese origin which denotes a cute expression or emotion felt by the user,^[13][14] but has more recently become associated with the furry fandom.^{[citation needed]}

In Brazil, sometimes combining characters (accents) are added to emoticons to represent eyebrows, as in ò_ó, ó_ò, õ_o, ù_u, o_Ô, or ( •̀ ᴗ •́ ).^[15]

• Seargeant, Philip (2019). The Emoji Revolution: How Technology is Shaping the Future of Communication. Cambridge University Press. ISBN 978-1-108-49664-3.
• Veszelszki, Ágnes (2017). Digilect: The Impact of Infocommunication Technology on Language. Berlin: Walter de Gruyter. ISBN 978-3-11-049911-7.