Uwu

codice_1, also used as codice_2, is an emoticon showing cuteness. The codice_3 letters represent eyes, while the codice_4 represents a mouth. 
Usage.
codice_1 is used to show cuteness, , or kindness. Overuse of the emoticon can also have a effect of annoying its receiver. The emoticon has been popular in the furry fandom. 
There's a more surprised variant, codice_6 (also connected with the furry fandom and the response, "what's this?") that may mean cuteness, as well as curiosity and confusion.
History.
codice_1 is known to exist back as far back as 2005, in an anime fan fiction. The origin of the word is not known, with many people believing it to originate in Internet chat rooms. By 2014, the emoticon had spread across the Internet into Tumblr, becoming an Internet subculture.
The word codice_1 is included in the Royal Spanish Academy's word observatory, defined as an "emoticon used to show happiness or tenderness".
Notable uses.
In 2018, the official Twitter account tweeted "uwu" in response to a tweet by an artist on October 22, 2018.
In 2020, the U.S. Army Esports Twitter account tweeted "uwu" in reply to a tweet by Discord's Twitter account, which was met by lots of backlash from Twitter users. This event ended in a trend of attempting to get banned from the U.S. Army Esports Discord server as fast as possible, with a common technique being to link to the Wikipedia article, United States war crimes.