Which term is used to describe the usable data that crosses a given point in a network?

The term that describes the usable data crossing a given point in a network is "Goodput." Goodput refers specifically to the amount of useful data that is successfully transmitted over a network, minus any protocol overhead, retransmissions, or other non-essential data.

In many networking scenarios, it is important to understand not just the raw data that can theoretically be transmitted (which could be affected by various factors that create delays or require retransmissions) but rather the actual data that users are able to utilize. This is why goodput is a critical measure for evaluating network performance, as it offers a more accurate reflection of the user experience and efficiency of data transfer in real-world applications.

Understanding goodput helps network engineers and administrators optimize network performance by focusing on what is genuinely being delivered to end users, rather than what may be advertised theoretically in terms of bandwidth or capacity. Effective management of goodput is crucial in maintaining high-performance networks, especially in environments with high traffic or where bandwidth utilization is critical.