Requirements:

• Apache web server with the mod_rewrite module installed
• In WordPress's home directory,
• The FollowSymLinks option enabled
• FileInfo directives allowed (e.g. AllowOverride FileInfo or AllowOverride All)
• An .htaccess file (if this file is missing, WordPress will try to create it when you activate "pretty" permalinks)
• If you want WordPress to update the .htaccess file automatically, WordPress will need write access to the file.