What are the key features of Brainfuck programming language and how does it differ from mainstream languages like PHP?

Brainfuck is a minimalist programming language with only 8 commands, making it extremely challenging to write and read code in. It operates on a simple memory model with a pointer that moves around an array of memory cells. In contrast, PHP is a high-level scripting language commonly used for web development with a wide range of built-in functions and libraries, making it much easier to work with.

// PHP code snippet
echo "Hello, World!";