Azure Functions

Many jobs are short, reactive, and intermittent. Running full-time infrastructure for thumbnail creation, scheduled cleanup, or queue-driven processing wastes money and pushes teams into patching and scaling work that is unrelated to the actual business logic.

Cloud hosting first reduced server procurement time, then platform services reduced runtime maintenance. Serverless emerged because a large class of workloads did not need permanent processes at all. Teams wanted to pay for actual execution and let the platform handle the rest.

Functions follow a trigger, execute, bind pattern. An event wakes the function, the function runs business logic, and bindings move data in or out of connected services with less integration code. Instead of writing connection setup and data serialization code yourself, a binding declaration tells the platform to handle the input/output plumbing. The platform scales the number of executions up or down so cost follows activity rather than uptime.

Functions and App Service both run code in Azure, but the execution contract is different. Functions are ideal for short-lived event handling with bursty demand. App Service is the better fit when a process should stay available for steady web traffic or long-lived connections.

Functions are a natural fit for patterns that look like 'event, short processing step, persisted result'. They work well for lightweight APIs, file processing, scheduled tasks, and asynchronous automation fed by event sources. They become awkward when the work is long-running, stateful, or requires persistent connection handling.