Files should be saved with Unicode - UTF-8 encoding.
The BOM should not be used. Unlike UTF-16 and UTF-32, there’s no byte order to indicate in a UTF-8 encoded file. The BOM can have a negative side effect in PHP of sending output, preventing the application from being able to set its own headers. Unix line endings should be used (LF).
You can read more about UTF-8 in UTF-8 Explained
The BOM should not be used. Unlike UTF-16 and UTF-32, there’s no byte order to indicate in a UTF-8 encoded file. The BOM can have a negative side effect in PHP of sending output, preventing the application from being able to set its own headers. Unix line endings should be used (LF).
You can read more about UTF-8 in UTF-8 Explained