PHPCS is the shortened name for PHP_CodeSniffer, which is a package to help monitor and keep code written to a coding standard. It comes with many coding standards built in with customization to change bits as needed. To quote themselves: PHP_CodeSniffer is an essential development tool that ensures your code remains clean and consistent. We could very well run this tool occassionally on our codebase by hand… But equally we can automate it instead.
