MathOverflow first came online on September 28, 2009!
Let's celebrate five years of MO!
I bought a delicious cake from the best bakery in the area to have with dinner tonight. I'm sure you will also find your own delectable way to celebrate this anniversary.
Some years ago, I asked community members How is MO useful for you? I think this is a great occasion to revisit that question. When asked about the motivations behind the site, MathOverflow founder Anton Geraschenko said: "I wanted MathOverflow to be useful for me!" So: