A carry-on bag is a small suitcase or backpack that travelers can bring onto an airplane. It is designed to fit in the overhead compartment or under the seat in front of you. Most airlines have specific size limits for carry-on bags, so it's important to check these rules before packing. This allows you to keep essential items, like clothes, toiletries, and electronics, close at hand during your flight. Using a carry-on bag can save time at the airport since you won't need to wait for checked luggage. It also helps you avoid extra fees that some airlines charge for checked bags. Packing wisely can make your travel experience smoother and more enjoyable, ensuring you have everything you need within reach.