what does a .htaccess file do? code example

Example 1: .htaccess

# Browser Caching
ExpiresActive On
ExpiresByType image/jpg "access 1 month"
ExpiresByType image/jpeg "access 1 month"
ExpiresByType image/gif "access 1 month"
ExpiresByType image/png "access 1 month"
ExpiresByType image/x-icon "access 1 month"
ExpiresByType text/css "access 1 month"
ExpiresByType application/pdf "access 1 month"
ExpiresByType text/x-javascript "access 1 month"
ExpiresByType application/x-shockwave-flash "access 1 month"
ExpiresDefault "access 3 days"

Example 2: .htaccess

# No extern use from your images
RewriteCond %{HTTP_REFERER} !^$
RewriteCond %{HTTP_REFERER} !^http(s)?://(www\.)?domainname.de [NC]
RewriteRule \.(jpg|jpeg|png|gif)$ https://domainname.de/hotlink.jpg [NC,R,L]