This is a simple program in Brainfuck
Basically store the String "Hello World!" in a variable (a char array) and print the chars every time a char is written
The idea behind brainfuck is memory manipulation. Basically you are given an array of 30,000 1byte memory blocks. The array size is actually dependent upon the implementation used in the compiler or interpretor, but standard brainfuck states 30,000. Within this array, you can increase the memory pointer, increase the value at the memory pointer, etc.
Thx to roachhd for the expanation