Not something you install and own — something you’re allowed to keep using as long as you keep paying.
Before cloud computing standardised the term, buying software meant buying a copy: a licence, a disc, a server to run it on, an IT department to maintain it. SaaS inverted that — the vendor keeps the software running on their own infrastructure, and the customer just logs in and pays monthly. NIST’s 2011 definition of cloud computing formalised SaaS as one of three standard service models (alongside Platform-as-a-Service and Infrastructure-as-a-Service): “the capability provided to the consumer… to use the provider’s applications running on a cloud infrastructure,” with the consumer managing none of the underlying servers, storage, or even most application configuration.
This is the default packaging for almost every AI product sold today, including the automations and chatbots this essay describes — a business doesn’t buy the AI, it rents access to someone else’s running instance of it. The “build a SaaS” instinct at the end of this essay is the natural next step for exactly that reason: once you’ve built one working automation for a client, packaging it as a subscription product is how you stop re-selling your own time.
Source: Mell, P. & Grance, T. (2011), “The NIST Definition of Cloud Computing,” NIST Special Publication 800-145.