Along with sprintf, one of the most important functions for string manipulation in C. Syntax similar to the printf family.

Here's a very brief example:

#include <stdio.h>

main() {

	int *x;
	char *s;

	sscanf( "256 blah", "%i %s", x, s );

	/*
	   x is now a pointer to 256.
           s is now a pointer to "blah".
	*/

}