Why do we always need to wait for 'launch windows' to get a rocket to space?

Artemis I launch has been ‘scrubbed’ a couple of times now. Why is a launch window so important, and what does scrubbing mean, anyway?

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Peregrine Mission-1: First US spacecraft due to land on moon since the Apollo missions in the 1970s lifts off, Science & Tech News

Why can't a rocket just be 'thrown off' Earth's surface? Launch windows are important

Why NASA had to cancel their Artemis 1 Moon rocket test

Firefly launching Space Force high-speed Victus Nox mission

Tech it to space: Why do we always need to wait for 'launch windows' to get a rocket to space?

JAXA Space Transportation Systems

To watch Artemis rocket launch, Space nerds swarm Florida

SpaceX has narrow window for Ax-2 launch - SpaceNews

Artemis 1 launch delay is the latest of many NASA scrubs

SpaceX Lands All 3 Boosters of Its Falcon Heavy Rocket

Artemis launch delays mean Moon probes' batteries are dying

Juice launch latest: Spacecraft is 'alive' - explorer sends back first signal on mission to Jupiter, Science & Tech News

How do space shuttles launch? - Quora