Bandwidth originally described how much information can flow through a connection at once, like how a wider pipe can carry more water than a narrow one. A high-bandwidth internet connection lets you download a movie in seconds, while a low-bandwidth connection might take hours for the same file.

In technology, bandwidth is the amount of data that can move through a cable or wireless connection in a certain amount of time. Today, we measure digital bandwidth in megabits or gigabits per second, numbers that tell you how fast data moves.

People also use bandwidth to describe mental capacity or availability. When your teacher says she doesn't have the bandwidth to take on another project, she means her time and energy are already fully committed. If you're studying for three tests while helping organize a school event, you might say you don't have the bandwidth to also join the soccer team right now. This metaphorical use captures the feeling of having only so much capacity to process or handle at once, just like a network connection can only transmit so much data before it slows down.