My Web browser Crashed

I am using Mozilla Firefox because it respond and download in my computer easily.The internet explorer is slow and sometimes it hang up if I open two or more web site.I used goggle's chrome in searching topics online.This week the Mozilla Firefox suddenly crashed and I don't know the reason.I feel annoyed if I am writing a post and it abruptly closed . The cousin do a maintenance of the computer.He set that post will be automatically save and open sites will be restore in case the Mozilla Firefox will crashed.It is good but how about the websites? oh well, my remedy here is to bookmark the important site for easily tracking back the information.