Microsoft designer Vincent Connare began working on Comic Sans in 1994 after having already created other fonts for various applications. When he saw a beta version of Microsoft Bob that used Times New Roman in the word balloons of its cartoon characters, he believed the typeface gave the software an overly formal appearance. He believed this was inappropriate for the aesthetics of the program, which was created to introduce younger users to computers. In order to make Microsoft Bob look more suitable for its intended purposes, he decided to create a new typeface with only a mouse and cursor, based on the lettering style of comic books he had in his office, specifically The Dark Knight Returns (lettered by John Costanza) and Watchmen (lettered by Dave Gibbons).[4]
He completed Comic Sans too late for inclusion in Microsoft Bob, and the typeface would go unreleased until the programmers of Microsoft 3D Movie Maker, which also used cartoon guides and speech bubbles, adopted it.[5] The speech bubbles were eventually phased out and replaced by actual sound, but Comic Sans stayed for the program's pop-up windows and help sections. The typeface later shipped with the Windows 95 Plus! Pack, and was the primary font of the Travel desktop theme. It was later included as a system font for the OEM versions of Windows 95. Finally, it became one of the default fonts for Microsoft Publisher and Microsoft Internet Explorer. Comic Sans is also used in Microsoft Comic Chat, which was released in 1996 with Internet Explorer 3.0.
Comic Sans is pre-installed in macOS and Windows Phone but not Android, iOS or Linux.[6] Comic Sans can be manually downloaded on iOS.[7]

A research article published by Cognition in 2010 showed disfluency could lead to improved retention and classroom performance. The article stated that disfluency can be produced merely by adopting fonts that are slightly more difficult to read.[28] In the case studies cited in the article, Comic Sans was used to introduce disfluency.[29] A 2010 Princeton University study involving presenting students with text in a font slightly harder to read found that they consistently retained more information from material displayed in fonts perceived as ugly or incoherent (Monotype Corsiva, Haettenschweiler, and Comic Sans Italic) than in a simpler, more traditional typeface such as Helvetica.[28]
More often, however, Comic Sans is described as especially legible, and is frequently used in school settings or as an aid for people with dyslexia.[30][additional citation(s) needed] Some people have reported that typing in Comic Sans has helped to clear writer's block, claiming that its casual appearance and high legibility create less mental tension.[31] Compared to other typefaces, Comic Sans has fewer rotated and mirror-image glyphs (ex. the letters "b", "d", "p", and "q"), has particularly wide letter spacing, and is sans serif[32][30][33] in general, although its capital "i" (I) has serifs to distinguish it from lowercase "l" (l).[34]