In this post, I'm going to talk about creating multiple WordPress installations on one domain. You can create one WordPress installation on any given domain, but any additional installations of WordPress will require a subdomain per new installation. No coding is required to complete this tutorial. You can use cPanel to install WordPress and create a subdomain.
So if you want to install three WordPress websites, you may install one under your domain name, another under a subdomain and another under a different subdomain. The subdomains have to be unique. There may be a limit on how many subdomains you can create on your hosting account, so check with your hosting provider first.
If you simply attempt to install WordPress in different multiple directories, or folders, under one domain, there will be reference issues. You can resolve reference issues that occur when installing WordPress in multiple directories under one domain name by creating a proper .htaccess file, but that's beyond the scope of this tutorial.
Note: There's no significant PR(pagerank) difference when using directories v.s. subdomains.
