If you have been following the growth of encryption on the web (https) and the fact that you can now get free SSL certificates (much like the one on this site) using Lets Encrypt, there is very little reason for not having your site running https, making your data encrypted between the server and the user, making everyone more secure.
Alongside developing lots of different websites in Drupal, we also maintain and administer a number of different servers. In this role we occasionally end up managing a number of different domain names. It struck us as interesting that many people don't really understand the difference between using the domain with or without www, for example www.willhallonline.co.uk and willhallonline.co.uk. They are technically two different subdomains of willhallonline.co.uk, however, it has to be stressed that they are different.