These mostly female characters originated from 2chan. Most of them represent operating systems. Others represent programs such as MSN or websites, such as Wikipedia. The bigger their tit size, the more space they hold. The puzzle girl you sometimes see in the top left corner of is an OS-tan herself.
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The concept of the OS-tans is reported to have begun as a personification of the common perception of Windows Me as unstable and prone to frequent crashes. Discussions on Futaba Channel likened this to the stereotype of a fickle, troublesome girl and as this personification expanded Me-tan was created and followed by the other characters. A large collection of these early images can be found on the web and some of the comics have been translated by readers on 4chan and idlechan. One of the early works to predominantly feature the OS-tans was an interactive Macromedia Flash animation showing a possible intro to an imaginary anime show known as Troubled Windows and is partly responsible for the spread of the OS-tans to English language imageboards. It is important to note that the OS-tans were by no means an original concept by the time of their creation and were predated by Toy's iMac Girl who was featured on a series of desktops released between August 1998 and March 1999
XP-tan is a dark-haired girl with ribbons in her hair and an "XP" hair ornament typically worn on the left side. As Windows XP is criticized for bloating a system and being very pretty without being as useful, XP-tan is commonly depicted wearing tight clothing with large breasts. Additionally, as a reference to the memory usage of Windows XP, she is often seen eating or holding an empty rice bowl labeled "Memory". Some variants include a version for XP Home known as "Homeko" who has green hair which she wears in a short ponytail with two large XP-shaped hairclips that cover her ears, as well as a rarer variant representing Windows XP Media Center Edition. The outfits worn by the two main variants are based on the loading lines at the Windows splash screen during startup.
Although a few variants exist, the most common operating system represented is Windows 2000 Professional. She is typically drawn as an intelligent, professional, reserved looking woman with short blue hair, glasses, and hair clips that resemble cat ears flanking a small white bonnet or ruffle, similar to a maid's bonnet, that shows the Windows logo. Her outfit resembles a swimsuit suggesting the Windows logo colors worn with long blue coat, alluding to the popular opinion that Windows 2000 is the most stable and dependable of the Windows operating systems. Due to the greater stability of Win2K compared with WinME, which was released near 2000, 2K-tan is often described as the guardian of ME-tan. The particular shade of blue used in most drawings is similar to the default Windows 2000 desktop color.
The design of ME-tan, the personification of Windows Me, is very much in line with the Japanese concept of cuteness. She is depicted with green hair in long pigtails wearing a maid outfit with an Exclamation mark badge on the front in the spirit of the Windows yellow error icon. While she is considered to be a hard worker, webcomics often depict her failing at anything she tries to do, often literally crashing and irritating her sisters. Additionally, when she is not frozen or out of control, she tends to do things showing a lack of common sense or knowledge, such as putting soda into a microwave oven or defending herself by swinging a scallion (This is a pun; a firewall program called "NEGiES" is pronounced like "Negi"(scallion) in Japanese.) In spite of, or perhaps due to, her pitiful plight, the clumsy ME-tan is considered by fans to one of the most beloved OS-tans.
Windows 98 and 98SE
While many variations exist the most common depiction of the Windows 98 operating systems is a pair of young girls. The OS-tan representative of the original release of Windows 98 is shown in a white and blue uniform that includes the Windows logo as part of a neck tie, navy blue hair, and a "98" hair clip. The Windows 98 Second Edition OS-tans is similar in appearance, but wears a green sailor school uniform with the letters "SE" on the front. Two early representations that are also seen are a pair of stick-limbed "Pocky" boxes with a face and version number drawn in crayon. This is a reference to Vulcan 300, a character from the Zatch Bell! anime series. These early representations are still used as a mecha piloted by the girls, dolls carried by the girls, or sometimes even as hiding places for them. SE hates cocks with passion. She is usually seen trying to castrate male characters with a bottle opener.
As Windows 95 is considered to be the oldest of the modern 32-bit Windows operating systems, it is usually represented as a traditional lady from the early modern era of Japan. She is typically depicted as a gentle-looking brown haired woman in a kimono, with a hair ribbon showing the four Windows colors. Her outfit is a traditional kimono and a hakama of Japan and she wears thick sandals, or geta (footwear), on her feet. These were a woman college student's typical clothes as seen in the earliest period during the course of the modernization in Japan (from the Meiji period to the Taisho perio]) and is a reference to the modernization of Windows in comparison to the modernization of Japan. Additionally, the pattern of her kimono is based on the file "hana256.bmp", which was used as a desktop wallpaper pattern in the Japanese version of Windows. She is typically depicted as engaged in drinking tea, cooking/serving meals or doing other housework. One recurring theme in stories is her unfamiliarity with newer, post Win-95 technologies, such as USB devices and broadband internet connections. She is also occasionally depicted wielding a katana in an aggressive manner, symbolizing that it was with her generation of operating systems that Microsoft finally achieved full dominance of the personal computer market.
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