.htaccess

.htaccess files affect the directory they are placed in and all sub-directories. This means that a htaccess file located in your root directory (yoursite.com) would affect yoursite.com/content, yoursite.com/content/contents, etc.
The .htaccess file can affect these things and much more:
- Error Documents
- Password protection
- Enable SSI via htaccess
- Deny users by IP
- Change your default directory index page
- Redirects
- Prevent viewing of htaccess
- Adding MIME types
- Prevent hot linking of your images
- Prevent directory listing