Hopefully means with hope or in a hopeful manner. When you look hopefully at the sky on the morning of your field trip, you're watching the clouds with hope that the rain will hold off. When a scientist hopefully tests a new theory, she's conducting the experiment with genuine hope that her idea will prove correct.

People also use hopefully at the beginning of a sentence to mean “it is hoped that” or “I hope that.” You might say, “Hopefully, we'll finish the project before lunch,” meaning you hope the project will be done by then. Some English teachers and writers object to this second usage, arguing it's imprecise because it's not always clear who is doing the hoping. But this meaning has become so common that most people accept it, even if a few sticklers remain unconvinced.

The key difference is this: when you act hopefully, you're doing something while feeling hopeful. When you use hopefully to start a sentence, you're simply expressing hope about an outcome. Either way, the word carries a sense of optimism and positive expectation about the future.