The original sequences were a series of essays written by Eliezer Yudkowsky between 2006 and 2009 on the blogs Overcoming Bias and Less Wrong. About half of these essays were organized into a number of thematically linked "sequences" of blog posts--hence the name.
In 2015, these sequences were edited into an ebook, Rationality: From AI to Zombies. The ebook leaves out some of the original posts, as well as adding some essays that were written by Yudkowsky during the same time but never previously collected into a named sequence. This page will serve to collect the older, deprecated sequences.
Bolded essays are more important than other posts in the sequence -- and big bolded essays even more so -- while italicized essays are relatively unimportant. Some essays are also indented to indicate that they are tangents or self-contained elaborations upon a previous essay.
Most important posts:
Seeing with Fresh Eyes
Overly Convenient Excuses