Sadly, Dennis Ritchie passed away today; there is a nice tribute to him here
For anyone who ever learnt C programming back in school, you will, like me, probably have started out with the seminal text "The C Programming Language" written by Ritchie and Brian Kernigan.
Ritchie was the co-creator of the C language - which is arguably the foundation of much of the modern software we use (though in many cases it has been superseded by Object Oriented languages, particularly C++) - but he was also one of the inventors of the UNIX operating system. He may not have been as charismatic or as well known as Steve Jobs, who passed last week, but he is arguably as important in the history of computing.
ESET expresses our sincerest sympathies to Dennis Ritchie's friends and family. The world is better for his having been in it, and that's probably the greatest legacy anyone can leave.
Update: In case you didn't reallise the significance, iOS, Mac OSX and Android are all based on UNIX like systems (Thanks to Shuveb for pointing that out)