When a server slows down, top gives you a list of processes, but it does not immediately tell you whether the real problem is CPU, memory, disk I/O, or network activity. You often end up opening free, df, iostat, and ss separately to get the full picture.
Imagine receiving an alert that a web server is responding slowly. You SSH into the server and run top. CPU usage looks normal, but that does not rule out memory pressure, disk contention, or heavy network traffic. You need several other commands to investigate each resource.
btop brings much of that information together in a single terminal interface. It displays per-core CPU usage, memory and swap consumption, disk I/O, network throughput, and running processes using live graphs and interactive panels. You can filter and sort processes, inspect resource usage, and customize the interface without leaving the terminal.