What's depicted
The emoticon is built from keyboard symbols and Japanese script characters. The dash and the "¯" mark represent arms raised in bewilderment, the eyes and mouth are made up of a circle, an underscore, and parentheses, while the character ツ, the katakana "tsu," serves as a stand-in torso. Together they form a figure that has thrown up its hands and is looking at the other person in complete confusion.
The canonical version, more common in English-speaking communities, is written as ¯\(°_o)/¯: instead of the Japanese character, it has a round face with wide-open eyes. In the Russian-speaking world the version with ツ took hold, which is why it's recognized as "Pozhimalkin." Both versions convey the same emotion, and the difference is more a matter of habit and taste than meaning.
Origin
The emoticon's exact author and the first place it was published have not been established. It's believed the device arose in text chats and on forums in the early 2010s, where graphical emoji were lacking but people wanted a quick way to convey an ironic shrug. The look with the ツ character is tied to Japanese text symbols that were widely used at the time on the Western internet for elaborate "kaomoji."
The version with the Japanese character spread through Twitter, forums, and messengers and entered common use among users worldwide. The name I Dunno LOL and the Russian version "Pozhimalkin" formed within communities that encountered the emoticon through everyday chat rather than through one specific publication. In the catalog the meme is dated to 2014, matching the period of its mass spread; the exact date of its first appearance is hard to pin down.
How it's used
The emoticon is placed at the end of a short line when someone wants to say "I don't know," "I don't care," or "oh well." Typical captions look like this: "Where are the keys? ¯\_(ツ)_/¯" or "Why is the server down again? ¯\_(ツ)_/¯" It works as a polite disclaimer: the other person understands there's no answer, and no one is obligated to come up with one.
In chats, the emoji often serves as a reply to a question that has no clear-cut answer by nature: a matter of taste, a pointless task, or a tricky bug nobody managed to fix. Variations include raised arms, captions placed inside images, and whole sequences of panels where the shrug becomes the punchline of a short comic.
Why the meme caught on
The main reason for its staying power is that the emoticon conveys both an emotion and an attitude at once. The shrug is short, understandable without translation, and needs no explanation. It expresses three things at once: ignorance, indifference, and a light resignation toward what's happening.
The emoji also works well in situations that call for irony. It creates a comic effect through the contrast between a serious question and a carefree gesture, and the ツ character gives it a visual accent that makes it stand out among ordinary parentheses. That's why the emoticon moves easily from chat messages into image captions and discussions, staying recognizable in any setting.