"Academia.edu is not a university or institution for higher learning and so under current standards it would not qualify for the '.edu' top-level domain. However, the domain name 'Academia.edu' was registered in 1999, prior to the regulations requiring .edu domain names to be held solely by accredited post-secondary institutions. All .edu domain names registered prior to 2001 were grandfathered in, even if not an accredited post-secondary institution."
Unfortunately, as far as I can tell neither of the links that wikipedia links to actually contains the 1999 date and if academia.edu was founded in 2008 then that was after the rules for transfer of a .edu domain were tightened. So there is some real detail missing from how they got the domain name.
I work in a public high school and this restriction on .edu is a source of frustration for me- the US-based and post-secondary restrictions on .edu domains are terrible.
from a comment by count in different thread on this page:
"They didn't buy it before the rules were put in place. They launched in 2008 as a company, and the the .edu was restricted to accredited institutions in 2001."
"Academia.edu is not a university or institution for higher learning and so under current standards it would not qualify for the '.edu' top-level domain. However, the domain name 'Academia.edu' was registered in 1999, prior to the regulations requiring .edu domain names to be held solely by accredited post-secondary institutions. All .edu domain names registered prior to 2001 were grandfathered in, even if not an accredited post-secondary institution."