Service is the formal delivery of the summons and complaint that gives a court authority over the defendant and starts the clock to respond. It is technical, and defects are consequential.

Methods vary by jurisdiction and by defendant. Personal delivery is the baseline. Companies are typically served through a registered agent or an officer. Substituted service — leaving papers at a residence with a suitable person, or service by mail, publication or electronic means — is generally permitted only in defined circumstances and often only with court permission after diligent attempts.

Why it matters. A judgment entered without proper service is vulnerable to being set aside, sometimes long afterwards. Defendants who discover a default judgment often succeed on that ground alone.

Deadlines. Rules typically require service within a set period after filing, with dismissal as the sanction for missing it absent good cause. And the response period runs from service, not from filing.

Waiver. Many systems allow a defendant to waive formal service, often with an incentive of a longer response period. Waiving service does not waive jurisdictional objections, which is worth knowing on both sides.

For companies: keep the registered agent current. Service on a lapsed agent is the most common route to a default judgment nobody knew about.