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How do you safely access scoped services like a DbContext from within a BackgroundService, which is registered as a singleton? How should exceptions be handled inside a BackgroundService's work loop to prevent one failure from silently stopping all future processing? How do you implement a periodic scheduled task using PeriodicTimer instead of Task.Delay, and what problem does it solve? How do multiple independently-registered BackgroundServices coexist within the same application, and does registration order matter? How does IHostApplicationLifetime let a BackgroundService react to application startup and shutdown events? How would you configure a BackgroundService to fail fast and crash the host if a critical startup dependency (like a message broker) is unreachable? How does graceful shutdown work for a BackgroundService, and how should ExecuteAsync respect the CancellationToken? How would you implement a producer-consumer background processing pipeline using System.Threading.Channels alongside a BackgroundService? How would you implement a cron-like scheduled background job (e.g., 'run daily at 2 AM') without a third-party scheduling library? How do background services interact with health checks to signal their operational status to an orchestrator like Kubernetes?
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ASP.NET Core › Background Tasks & Hosted Services

What is the difference between IHostedService and the BackgroundService convenience base class?

Intermediate

Answer

IHostedService is the low-level interface with just StartAsync and StopAsync methods, giving you full control for services that don't have an inherent continuous loop (like something that just registers/deregisters once at startup and shutdown). BackgroundService is a convenience base class implementing IHostedService specifically for the common 'continuous work loop' pattern, handling the StartAsync/StopAsync plumbing so you only write ExecuteAsync.
// Direct IHostedService: no continuous loop needed
public class MetricsRegistrationService : IHostedService {
    public Task StartAsync(CancellationToken ct) {
        MetricsRegistry.Register("my-service");
        return Task.CompletedTask;
    }
    public Task StopAsync(CancellationToken ct) {
        MetricsRegistry.Unregister("my-service");
        return Task.CompletedTask;
    }
}
Real-world example A service that simply registers the application with a service discovery system at startup and deregisters at shutdown implements IHostedService directly, since it has no ongoing loop -- unlike a queue processor, which extends BackgroundService instead.

Common follow-ups: Why does BackgroundService exist if IHostedService already covers this case?;Can a single class implement both patterns for different concerns?

Hosting Models: Kestrel IIS & Reverse Proxies;Dependency Injection
All 15 Background Tasks & Hosted Services questions