Many of the features on Nexus sites are limited to members only. Registration is fast and painless but necessary to make full use of the site. Why do we require you to register? Simply put, it's for our security to ensure the people who make use of this site can be moderated properly. We like our sites clean and tidy you see. Plus there are certain features of the site that just wouldn't work without having a membership system; like file uploads, commenting and endorsing.