Extensions
Side-by-side customisations to Business Central or Dataverse that don't modify the base application, enabling clean upgrades.
Extensions are the modern, supported way to customise Microsoft business apps. In Business Central, an extension is an AL package that adds new tables, pages, code, and integrations alongside the base application without modifying Microsoft's own objects — which is why upgrades stay non-breaking. Extensions are installed per tenant, published through AppSource, or pushed by a partner. Dynamics 365 CRM-side apps use a similar concept through solutions in Dataverse, which package tables, forms, security roles, flows, and Power Apps. Both models replace the older practice of editing the base product directly.