Reddit glossary
What is TL;DR on Reddit?
TL;DR stands for too long, didn't read, and it is a one or two line summary at the end of a long post.
Redditors often add it at the bottom of long posts so busy readers get the point fast.
A good TL;DR is honest and short. It is not a place to sneak in a sales line.
If you are promoting something
If you write long answers, add a TL;DR. Most people skim first and read second.