Question: I want to write a PHP code snippet in the question or answer. I searched that but Stack Overflow can insert only HTML, CSS, JavaScript snippet code.

How can I insert a PHP code snippet like below?

JavaScript snippet example:

```js
console.log('hello world');
```

Answer: 
If you understand the difference between client- and server-side code and the security implications thereof, you will understand why this is not, and probably never will be, a feature on Stack Overflow.
No, probably not, you should use code blocks instead as specified in the other answers.

Adding to the other answers, here are a few extra points:

* The PHP stack snippets would use up all the server CPU/RAM which would make the whole experience slightly slower for everyone
* The PHP `mail()` function could be used to send spam email to lots of people, and, again, could overwhelm the server
* You can do all sorts of destructive things with PHP, including changing databases, and even deleting files.
* Too many requests for PHP could even put Stack Overflow offline. Yikes.