Linux and about every package you'd find on a base Linux system are written with this language, although it is probably one of the worst languages to start programming, with due to its steep learning curve. C's popularity has been fading, but you should probably wet your feet at least a little bit with it at some point because of its persistent popularity. One compiler that is certainly worth peeking at is GNU's C Compiler, GCC. http://gcc.gnu.org/
The two advantages of C are that it allows you to do low-level gunky stuff if required and has a wide range of libraries (SDL, GTK, the win32 api, OpenGL) that are native to C.
Special Topics: AboutPointers
Thought i'd put in the always-needed hello world example code. =)
#include <stdio.h>
int main(void) {
printf("Hello narasimhareddy!\n");
puts("hai narasimhareddy");
return 0;
}