Sector Y is a yo-yo website dedicated to teaching beginner players more advanced yo-yo tricks. The site is founded and run by Gabriel Lozano (screen handle Citadel) and was originally hosted by yoyoing.com, however it is now an independent site.
Sector Y was extremely influential in the pre-youtube era (1999-2004), the single largest source of yo-yo videos on the Internet at the time. It hosted a variety of step-by-step trick descriptions (picture and text based), as well as Spin Dox clip videos, a huge library of individual trick videos, and also select contest freestyles.
After a long hiatus from activity, Citadel revived Sector Y in 2009, restructuring the site as v2.0. As the yoyoing.com message board went defunct, this is when Sector Y moved to its independent URL.
In 2012, the website again retired from active production.