No different to others mentioned here: contacted via LinkedIn, one screening call (45mins), then on-site with 4 x 45mins interviews. Overall, the algorithm questions are not particularly hard. I have interviewed with FB twice, and both times felt the sessions went well (although considerably better the second time), but no offer either time. You won't get detailed enough feedback to know where you might have tripped up, if anywhere, though. From their point of view, I think this is understandable, but makes it harder to deal with the rejection; if you had fouled up every session you would feel better than if you basically answered all the questions, with seemingly positive feedback from each interviewer, yet not got an offer... As noted elsewhere, it's probably best to be stoic about the whole thing and accept that they have so many candidates they probably apply a "benefit of the doubt" policy that works against in their favour; ie. I would imagine they employ a sort of "thumb up", "thumb down" policy. They are, however, very pleasant and expect to have a positive experience of the process even if the result is not what you might want yourself.