If you are operating a website built on WordPress, then eventually you will need to modify certain files or fix certain issues related to your Theme or Plugins.
This included video tutorial shows WordPress file structure of wordpress as well as show you its Database structure.
WordPress File Structure
Although you can actually change file structure of your WordPress installation, it is highly encouraged and you should leave the file structure to its default settings.
Recently few of RankYa fans has asked about WordPress security and how web hosting companies are offering Ad-On WordPress Security services. Well the best way to protect your WordPress is to make sure that you have regular backups of your entire website. This will ensure that regardless of what happens to your website, you can quickly restore it.