should I add www ?

Technically either is fine, but you want to stick with one or the other for reasons of pagerank, links, cookies, etc. Search engines see them as two different sites.

I don’t know the technical history of www but it’s superfluous and redundant for my purposes.

Thanks Christian, I agree with you, but would like to get more information on the pro’s and con’s. Not having much luck searching so far

I’ll suggest you stick with one format for consistency. The reason is that say you use https://mydomain.com

When you mention your site in third party websites even for Backlinks, Promotion and while leaving comments on other blogs, google treats both the URLs https://mydomain.com and https://www.mydomain.com differently.

Technically speaking, although they point to the same root Search Engine does not know of this fact and therefore may penalize your site for duplicate content as it’ll feel there are two different sites with same content.

For SEO’s perspective its advisable to use one and stick with it. Also, use redirection from https://www to https:// or vice versa from the Domain Control Panel so that if by chance you use a different from somewhere the Page Rank benefits get transferred to the one you want.

I hope this helps

Thanks vaibhavkanwal that is what I have discovered.

It seems that if starting a new site, then don’t use www – because it is not necessary anymore

If on an old site that is or was www, then stick with it, as you say, so not to confuse search engines and being penalised for same content on two websites.

As others have mentioned, consistency is key, once you make your decision stick with it. I personally do not use the www and it seems that most people are not using it as much. My advice is to drop the www

FYI, Matt Mullenweg also thinks you should drop the www and if anybody could be said to be an expert with WordPress, it’s him.