MathOverflow is a mathematics question-and answer website meant for questions at the graduate student level and beyond. It is part of the Stack Exchange Network.
The site launched on September 2009. I started participating in January 2010. My participation has been sporadic, though it was higher in the early years. For the most part, apart from the first few months, I go on the site only when I have questions of my own to ask or search for.
My profile is here. You can use this to browse my questions and answers.