I am asking for confirmation that I correctly understand the difference between WordPress Multisite vs. shared hosting. I am doing some preliminary research for a local WISP who is interested in expanding into local web hosting.

If I understand correctly, WordPress Multisite supports multiple WordPress sites from the perspective of being driven by a single instance of WordPress. Multisite uses a single MySQL (MariaDB) database for all sites and several tables are duplicated for each site. A single database probably is not ideal when a customer wants to move all data to a different host provider.

Shared hosting supports multiple web sites from the perspective of the server --- a single instance of Apache running multiple web sites using name-based virtual hosts. While a single instance of Apache is installed with shared hosting, a separate MySQL (MariaDB) database is created for each WordPress customer and WordPress is installed in each customer's /var/www/customer/public_html directory. Unlike Multisite, this means multiple instances of WordPress.

Am I understanding correctly? Feel free to correct me as necessary, preferably without two-by-fours.

Thanks much!

Yes this is correct. You should never advice that customers share databases and wordpress instances, asking for trouble there. You can do tiered sort of setups with Plesk or cPanel/WHM which would be ideal to keep everything centralized but keep customer data isolated.

Okay. Thanks. Am I correct that shared hosting means multiple but separate instances of installing WordPress?

Shared hosting means that a website exists on a server with many other websites.

It is the server that is being shared. A shared server may host 100s, even 1000s of websites. Generally, the public ip of the website is actually the ip of the server; the Apache (or other engine) then directs an incoming call to the appropriate website based on the domain name.

Here's pretty good basic definition of the concept: http://searchsoa.techtarget.com/defi...shared-hosting

My little website is on a shared hosting server. It (my website) contains effectively three sites, each in its own directory: two that are plain HTML sites and, yes, the WordPress install is an independent install from any other shared hosting site on that server. I could remove my WordPress install and not affect any other website on the server.

That is what I am trying to distinguish. I understand the server/apache part. I am unclear about how WordPress integrates. If all customers at a hosting server are using WordPress, is WordPress installed separately for each customer in the customer's /var/www/customer/public_html directory?

I am not worried about disk space if that is the case. I justwant to convey the correct information in my research.

Looks good to me.
/var/www/customer1/public_html - Would need a single instance of WP installed AND <db_name1>.
/var/www/customer2/public_html - Would need a single instance of WP installed AND <db_name2>.
/var/www/customer3/public_html - Would need a single instance of WP installed AND <db_name3>.

This arrangement is functionally the same as a the MU version of WP, however with some sysadmin overhead.

Hope that helps.

Good enough. Thanks. The unzipped size of the WP (core) archive is 22 MB --- not much at all compared to hard drive sizes these days.

You are very welcome.