Do you know what "AFAIK" is?

I didnt and that gave a friend a chance to laugh at my expense yesterday :-) I had asked him for some information and he bagan his email with the word 'AFAIK". When I replied back I wrote 'What is AFAIK? As far as I know, its neither an English word nor Hindi. Is it some slang in an Indian language that I dont know?'. Promptly I got an email back with a lot of smileys which said 'AFAIK means As Far As I know" :-))) I almost died with shame!!