SaaS

SaaS stands for Software-as-a-Service. It refers to software delivered as a managed cloud subscription, where the vendor owns the infrastructure, patching, backups, and upgrades, and the customer accesses the service over the internet. All Dynamics 365 apps — Business Central, Finance, Supply Chain Management, Sales, Customer Service, Field Service, and the rest — are sold primarily as SaaS, hosted on Microsoft Azure. SaaS shifts ERP and CRM from a capital project with multi-year on-premise infrastructure to an operational subscription with continuous updates, but in return constrains customisation to supported extensibility patterns rather than direct database access.

In practice, the trade-off that catches organisations coming from on-premise software off guard is the loss of direct database access. A team used to writing a SQL query or a custom view straight against their on-premise ERP's database has no equivalent option on SaaS — every customisation and every integration goes through a supported API or extension model instead, which is slower to build but survives the vendor's own updates without breaking. This is the same trade-off that makes twice-yearly Business Central updates and F&O's continuous update model non-disruptive: nothing customers built ever touched the base objects the update is changing.

Where confusion shows up: "cloud" and "SaaS" get used as synonyms, but they're not quite the same thing — a company can run its own software on cloud infrastructure (Azure virtual machines, say) without that software being SaaS, because the company still owns patching and upgrades. SaaS specifically means the vendor operates the software as a service; the underlying infrastructure being cloud-hosted is a separate, related fact about where it runs, not what SaaS itself means.