A domain expires when its term ends without a renewal, either because auto-renew was off or because every renewal charge failed. What happens next depends on the extension, but it follows a pattern.
Straight after expiry
The domain stops resolving: the website and any email on the domain stop working, often within a day. The name is not yet available to others.
Grace period
Most registries hold the name for a period after expiry during which it can be renewed at the normal price. The length varies by extension, from a few days to several weeks. During this window a renewal from your account restores the domain, usually within hours.
Redemption
After the grace period many extensions enter a redemption phase, commonly around 30 days for global domains. The name can still be recovered, but only through the registrar and usually for a redemption fee set by the registry, which can be several times the annual price.
Deletion
After redemption the name is released and anyone can register it. Domains with a history can be picked up quickly by resellers, so this is the outcome to avoid.
What to do
Contact us the moment you notice, or better, the moment a renewal email arrives that you did not expect. We can tell you exactly where the domain is in its lifecycle and what recovery costs. The cheapest fix is always before expiry: keep a valid card on file and auto-renew on. See How domain renewals and billing work.