htop (Linux): ```bash sudo apt install htop htop ``` Displays real-time CPU and RAM usage. df -h: Shows disk usage in human-readable format. free -m: Displays RAM usage in megabytes. top: A classic tool showing CPU, RAM, and processes. For more advanced monitoring, install Netdata or Zabbix: ```bash bash <(curl -Ss https://my-netdata.io/kickstart.sh) ```