The Brief: TLDR stands for "too long; didn't read."

DEEP DIVE
TLDR (also stylized tl;dr) is used to introduce a summary to a large amount of text. Its use allows readers to skip reading a large amount of contextualizing information in favor of a more succinct version. For instance, a several paragraphs-long Reddit post in which the user describes his budding romantic feelings for his Art History professor, going into great detail about the context surrounding their relationship, might begin or end with “tl;dr I’m in love with my art teacher.”
TLDR can also summarize Instagram captions, Facebook statuses, or web articles. Sometimes the summary is used to highlight a personal take on an issue, usually in conjunction with a news story. It can be used in texting as a response to a lengthy message or to communicate disinterest:
Person 1: I had an amazing weekend, I went to a wellness retreat and learned a lot about myself and the world.
Person 2: TLDR
The abbreviation’s use has evolved to include the phrase “TLDR version,” as in requesting a TLDR version (summary) to a large amount of reading.
First Impressions of KH3
-Combat is enjoyable (also meaning VERY GOOD)
-Cutscenes and voice acting are the best it's ever been in the series
-Customization and upgrades are really interesting
-TWILIGHT TOWN TWILIGHT TOWN
-True genuine character interactions !!tldr: i love it pic.twitter.com/Ij8zb7X7Dv
— [Rei] (@gal_exe) January 29, 2019
How big tech allows right wing populists to use disinformation to win power while how our 'elites' and electoral regulation is asleep at the wheel. My latest @SunScotNational column (Tldr: we are all guinea pigs in a lab that could destroy our democracy) https://t.co/12WRpnf7P3
— Peter Geoghegan (@PeterKGeoghegan) January 27, 2019
When somebody cc's you on a months-long email thread without giving you a tldr. pic.twitter.com/L4fSkXbDhU
— ah, brie! (@tinyangryperson) January 29, 2019