Where it sits
It started at the dismissive end and has drifted, steadily, toward the helpful one.
Tell it apart
| Aspect | As a reply | As a summary |
|---|---|---|
| Who writes it | The reader | The writer |
| Tone | Dismissive | Helpful |
| Followed by | Nothing | A one-line version |
Posted by someone else under your long message, TL;DR is a brush-off. Written by you above or below your own long message, it's a courtesy.
What it doesn't mean
It began as a brush-off, but Dictionary.com also records it as a noun for a summary of a lengthy post, and that's now one of its most common uses.
What it really means
TL;DR has done something unusual for internet slang: it has become more polite with age. It stands for "too long; didn't read", and it started as exactly what it sounds like, a brush-off posted under someone else's long message.
According to Wikipedia, which cites the Oxford English Dictionary, its earliest known use is a 2002 message on a Usenet newsgroup about Nintendo games. By 2009 it was in print slang dictionaries, and in 2013 Oxford Dictionaries Online added it.
Somewhere along the way the writers took it back. If people won't read your long post, you can save them the trouble: put "TL;DR:" at the top or bottom and give the one-line version. Dictionary.com records this as a separate noun sense, a summary of a lengthy online post. It's now routine in work chats, forum posts and long texts about why you're late.
So the same four letters can mean opposite things depending on who writes them. Under your message, from someone else, it's a shrug. On your message, from you, it's a kindness. The semicolon is optional either way.
Where it comes from
too long
the semicolon that splits the two halves
didn't read
Unusually, it keeps a punctuation mark inside the abbreviation. Many people drop it and write tldr.
- 2002
Earliest known use, in a message on the Usenet newsgroup rec.games.video.nintendo (Wikipedia, citing the OED).
- 2000–05
Dictionary.com's first-recorded range for the term.
- 2009
Appears in the print slang collection Mo' Urban Dictionary (Wikipedia).
- 2013
Added to Oxford Dictionaries Online (Wikipedia).
In real life
- Text: "long story about the train, but tl;dr I'll be 20 minutes late"
- Text: "TL;DR: the party's moved to Saturday, details below"
- Text: "tldr the shop was closed so I got pizza instead"
Questions
Q01What does TL;DR mean?
"Too long; didn't read." As a reply it means your message was too long to bother with. As a heading ("TL;DR:") it introduces a short summary of a long message.
Q02How old is TL;DR?
Wikipedia, citing the Oxford English Dictionary, gives its earliest known use as a 2002 post on a Usenet video-game newsgroup. It was added to Oxford Dictionaries Online in 2013.
Q03Is it rude to write TL;DR?
Replying "tl;dr" to someone's long message can be rude. Putting a "TL;DR" summary on your own long message is considerate, and common in work chats and forum posts.
Q04Do I need the semicolon?
No. TL;DR, TLDR and tldr are all common. The semicolon is traditional, but plenty of people drop it.