Should you use ‘www’ as subdomain or not?

I thought about changing my domains and removing the www subdomain in favour of using just the bare naked domain. It turns out that this isn’t a good idea, as this answer on Stack Overflow to a thread discussing this topic shows:

“Due to the dot rule with cookies, if you don’t have the ‘www.’ then you can’t set two-dot cookies or cross-subdomain cookies a la *.example.com. There are two pertinent impacts.”

You should read the whole answer. There are even more reasons: many people type www anyway, as they don’t know it only being a subdomain but thinking it’s necessary. But probably the most important reason is not to change your URL at all. So if you’re using your domain without a subdomain or with the subdomain www, keep it that way.

Or have fun 301 redirecting all your stuff.