- PHP owns the top-level namespace but tries to find decent descriptive names and avoid any obvious clashes.
- Function names use underscores between words, while class names use both the camelCase and PascalCase rules.
- PHP will prefix any global symbols of an extension with the name of the extension.
- Iterators and Exceptions are however simply postfixed with “Iterator” and “Exception.”
- PHP reserves all symbols starting with __ as magical. It is recommended that you do not create symbols starting with __ in PHP unless you want to use documented magical functionality.