Chilana's work "is one of the very first studies of Facebook's [design] process," said Wayne Lutters, a computer science associate professor at the University of Maryland Baltimore County, who moderated Chilana's talk. Only recently has the company "slowly started opening its doors to outsiders," wishing to learn more about its development process, he said.

As a baseline, Chilana used the generally agreed upon principles of good software user interface design, as espoused by John Gould and Clayton Lewis in a 1985 paper "." Gould and Lewis stressed iterative design, a focus on user testing and user-focused design in general.

While many product designers tend not to be aware of such principles, Facebook relies heavily on such ideas, Chilana found. "Over half the interview participants explicitly identified user experience as a key factor in driving design on Facebook," Chilana said.

Facebook also values iteration. One engineer told Chilana that the company "will just try to get something out there, make sure it is reasonable and then iterate on the design based on how people are using it," she said. "Design is hard," another designer told her. "Just doing our best with very smart people, we screw up plenty."

This approach is not always easy given the size and variety of Facebook's user base. One engineer told Chilana that "once you get away from the core features, it is not necessarily obvious that there is a magic way that a feature could work in a way that everyone can find value in it," she said. Engineers often have to design for the least common denominator, she said. Many proposed advance features don't get implemented because the adoption rate would be too small to make the work worthwhile.