Legally means according to the law or in a way that follows the official rules of a country or place. When something happens legally, it's done following the rules that society has agreed on.

A driver's license lets you drive legally. Without one, you'd be breaking the law. When a business operates legally, it pays its taxes, follows safety rules, and treats workers fairly. When someone becomes a citizen legally, they complete all the required steps that the government sets.

The opposite is illegally, which means breaking the law. Downloading a movie illegally means getting it without paying or having permission. Parking illegally means leaving your car where signs say you can't.

Sometimes people say “That's not legally possible” when rules prevent something from happening, even if it seems like it should be allowed. For instance, a ten-year-old can't legally sign a contract or own property, no matter how responsible they are. And just because something is legal doesn't always mean it's right or fair: laws change over time as societies learn and grow.