A small note on .htaccess file.
What is .htaccess?
.htaccess is a configuration file for use on web servers running the Apache Web Server. When an .htaccess file is placed in a directory it is detected by the web server and gets exectued.These .htaccess files are used to alter the configuration of the Apache Web Server to enable/disable additional functionality and features that the Apache Web Server software has to offer.
A sample .htaccess file :
AuthName "security check"
ErrorDocument 401 /error_pages/401.html
As per the above .htaccess file, it enables password protection on the directory; it offers redirection to a custom error page if a user fails to login correctly.
This is just a basic example.
.htaccess files are very powerful and they can be extremely fine tuned to meet your needs.