Do I have to use “www.”?

You can have either, see no-www.org/

…. but settle one one and keep to that forever otherwise you may experience issues with Google when it thinks it has duplicate content on https://www.domain and domain.

Good point, though Google really ought to be able to cope with that one.

I think that the ‘www.’ should be removed automatically, meaning both are accessible.

so you think i should redirect “www.domain” to “domain”?

yup, that means it’s still available if there are any old links.

you may want to do it the other way round though depending on the look of your URL.

Your web host is more of a factor here than anything else, or rather, how your web server is configured. Mine treats https://www.domain.com and domain.com as the same place on the server, and returns identical files. I would speak to your web host about this if it’s important to you to support both at the same time.

so you think i should redirect “www.domain” to “domain”?

Or vice-versa, whichever you prefer. It makes things a lot easier to redirect one to the other for several reasons.
-It avoids search engines treating your site as two sites
-It gives you a standardized format for any stats you may be compiling
-It just generally adds consistency and makes your site look a bit more professional…

I personally prefer it without the www at the beginning, but to each his own. I redirect all www traffic to my normal domain name. Works nicely. Also makes configuration a heck of a lot nicer for a lot of software packages, including WordPress.

OK how do I redirect it?

You can add this to your httpd.conf, or possibly to your .htaccess file. Change the domain name, obviously.

Also, remove the space in http, I had to add that because of the way this forum works.

RewriteCond %{HTTP_HOST} ^www\.example\.com$ [NC]
RewriteRule ^(.*)$ ht tp://example.com/$1 [R=301,L]