Ask Ubuntu is part of the Stack Exchange Network. You will find most of your answers on the /about page there, and on meta.stackoverflowmeta.stackoverflow and Area 51. Both of these are also part of the Stack Exchange network.
Stack Exchange was built to expand Stack Overflow beyond just programming. Some Ubuntu community members then pushed for their own site through Area 51.
The site went through four phases:
- A definition phase: where people defined what on and off-topic posts would look like.
- A commitment phase: where people committed and said they would actually use the site.
- A private beta: where those who committed gained access and started using the site.
- A public beta: same as private beta but with a wider audience.
At each phase, the the site had to prove it was worth going to the next phase. Finally after all of those steps, the site went "public" in October 2010 and was rebranded Ask Ubuntu.