Round-trip delay

When you talk to someone on the phone or on the internet, there is a little bit of time that it takes for your message to travel to the other person and for their response to come back to you. This time is called "round-trip delay." It's like a game of catch: you throw the ball to your friend and it takes a little bit of time for them to catch it and throw it back to you. The round-trip delay is the time it takes for the ball (or your message) to go back and forth between you and your friend (or the person you're talking to on the phone or internet). The longer the round-trip delay, the longer you have to wait to get a response from the other person.