Modifying your .htaccess file can really help boost the speed of your website plus help eliminate annoying referral spam. But messing around with your .htaccess file can be dangerous if you are not careful and have a good sense of what you are doing.
I will try to cover some important things you can do by making small modifications to it, starting with how to Improve Security.
While there are many plugins out there that can help you with WordPress security, just adding some code to the .htaccess file can help more than adding another plugin. Plugins need updating and if their developers decide to stop supporting it, you can have problems on your hand. But by adding a small snippet of code to your .htaccess file, you can quickly secure your site without worrying about updates and lack of plugin developer support. Elegant Themes and WP Beginner have great posts on how to set up your .htaccess files for security, see them here: