WaaS stands for Website as a Service. Lets break it down a bit.
What is 'as a Service'?
It refers to products and services that are made available to consumers over the web. Clients might be logging in and using a software (for example Brizy PRO) on the web.
The business model
Not every 'as a Service' product is paid for on a monthly subscription basis, but this is usually the payment model used. The majority of 'as a Service' products will have a monthly or annual payment plan.
Website as a service
A website is perfect for the "as a service" model. Websites, and especially business websites can be rented to clients. Users will get the full use and benefits while somebody else (you) manages the platform: updates, security, hosting, website building tools and so on.
Some examples of popular Website as a Service platforms are: Squarespace, Wix and WordPress.com.
What is important is that a Website as a Service (WaaS) is not defined by only one rule and there are a few that define it.
So, if you’re using a multi-site capable WordPress website, that is either selling pre-made websites as “choosables”, or renting websites existing designs with the option to customize, then you’re a WaaS.