What does TLDR mean?

Can you explain to me what TLDR stands for and what it's commonly used for in the context of reading and understanding lengthy texts, particularly in the world of finance and cryptocurrency? I've seen it in a few articles and discussions but haven't quite grasped its full meaning and purpose. It seems to be a shorthand for something that helps readers quickly grasp the main points of a piece, but I'd appreciate a more detailed explanation.