The main purpose of .htaccess file was to allow per-directory access control.
".htaccess" files affect the directory and sub-directories in which it is placed.
Use of Htaccess.
Authorization, Authentication : A ".htaccess" file is often used to specify security restrictions for a directory. The .htaccess file
is uses a ".htpasswd" file which stores valid usernames and their passwords .
Rewriting urls : We use ".htaccess" file to rewrite long, complicated urls to shorter and more memorable ones.
Blocking : By ".htaccess" file we can block users by IP address or domain.
Also, use to block bad bots, referrers and rippers.
SSI : Enable server-side includes.
Directory listing : ".htaccess" file Control how the server will react when no specific web page is specified.
Customize error pages : ".htaccess" file used to customize the page that is shown when a server-side error occurs.
Cache control : ".htaccess" file allow a server to control caching by web browsers and proxies to reduce bandwidth usage.