www

• www stands for World Wide Web and is a relict from the early internet days
• . is hard to spell in english (double you, double you, double you, double you, dot)
• . is just an optional subdomain
• A domain without www is called apex-, naked- or bare-domain
• Print designers like the look - print ads mostly include the . prefix
• Young people tend to skip . when typing in a domain in the address bar of the browser
• Old people always type . before they type the actual domain name
• Some web masters forget to set up this subdomain > 404
• . is coming back with modern cloud hosting (CNAME records, CDNs …)

Sources: 1, 2, 3