I mean this in a friendly constructive way, and realize you may not be a kid. But while there's lots of positive innovation happening in culture and esp related to the Internet, I feel strongly that "tl;dr" is not one of them, its a step backward. It's typically placed in the worst possible location (the very end rather than the very top/beginning) and it's far less likely to be understandable than "summary". It's also reinventing the wheel. Again, not a criticism of your comment, meant more for other readers, esp younger or less educated ones, who don't know about the word summary and how it is traditionally used to solve the need well already. :-)