htop

What is it?

htop is an interactive process viewer for Unix systems. It shows CPU, memory, and swap meters at the top, and a scrollable list of processes below, color-coded by CPU and memory use. Unlike the traditional top, htop lets you scroll with the arrow keys, kill or renice processes with function keys, and browse the process tree.

Why use it?

htop is the first tool most people install on a new machine, and for good reason: it answers "what is using my CPU right now?" instantly and legibly. The tree view makes parent-child process relationships clear, which is invaluable when a misbehaving script spawns hundreds of children. It is light enough to run on servers and works over any terminal.

Key features

• Per-core CPU meters with color-coded bars
• Memory and swap usage at a glance
• Scrollable process list with search and filtering
• Tree view of process ancestry
• Kill, renice, and follow processes from the UI
• Fully keyboard-driven with function-key shortcuts

How it compares

Against btop, htop is plainer but lighter and more universal — it is packaged everywhere and runs on minimal systems. Against top it is far more readable and interactive. Against bottom it is less graph-heavy and simpler. htop remains the dependable default for a quick look at system state.