Strange htaccess rules

Never this these before. Someone care to clue me in please:

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /

RewriteCond %{REQUEST_FILENAME} ^wp-content.*
RewriteCond %{REQUEST_FILENAME} ^wp-admin.*
RewriteCond %{REQUEST_FILENAME} ^wp-include.*
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>
# END WordPress

Reference: http://forums.digitalpoint.com/showthread.php?t=1656666

Looks like some form of security but nothing I'm used to.