.htaccess and its usage

  .htaccess is a configuration file which have following uses:
           - DirectoryIndex uses
           - used for restrict the user for access pages from website
           - redirect the urls
           - gives direction to server rather than search engine
           - create error document
           - compressing resources with gzip
           - add expires headers
           - enable and disable the additional functionality of apache webserver
           - prevent access to php.ini file
           - force scripts to display as a source code
           - ensure media files are downloaded instead of played
     
How to start with .htaccess?
   Syntax:
         <IfModule mod_rewrite.c>
             RewriteEngine On
             RewriteCond  %(REQUEST_FILENAME) !-f
             RewriteCond  %(REQUEST_FILENAME) !-d
             RewriteCond  %(REQUEST_FILENAME) !-l
             RewriteBase /
             DirectoryIndex index.php
             RewriteRule ^home index.php [L]
         </IfModule>
  Explanation:
     <IfModule mod_rewrite.c>
                                IfModule test whether mod_rewrite.c is included in apache. If mod_rewrite.c
is included, then it run. Otherwise it doesn't get run.
     RewriteEngine On
                                It tells apache to tuen on its RewriteRules.
     RewriteCond
                                RewriteCond check the condition.
%(REQUEST_FILENAME) is a variable based on url you request
!-f, !-d, !-l are extension added to regular expression.
where,
          f - file
         d - directory
          l - link
 if a file, taken from variable %(REQUEST_FILENAME) does not exist on the file system, then return true.
       RewriteBase /
                              It provide base for RewriteRules.                  
        DirectoryIndex index.php
                              It tells apache to which file is run first when server access to particular directory.
        RewriteRule
                              It redirect the urls.
RewriteRule ^home index.php [L]
      it means, when url get home, file index.php run.
              where,
                            ^ - starting point
                            $ - end point
                            L - tells the server to stop trying to rewrite a URL after it has applied that rule.