CPU Ticks

CPU Ticks average distribution within 1 minute. 
- user: normal processes executing in user mode
- nice: niced processes executing in user mode
- system: processes executing in kernel mode
- idle: twiddling thumbs
- iowait: waiting for I/O to complete
- irq: servicing interrupts
- softirq: servicing softirqs
System Load

Average CPU and IO utilization (for last 1 and 10 minutes).
Memory

Mem used = Mem Total - Cached - Buffers - Free
Cached - The amount of physical RAM, in kilobytes, used as cache memory.
Buffers - The amount of physical RAM, in kilobytes, used for file buffers.
Free - The amount of physical RAM, in kilobytes, left unused by the system.
Swap used - The amount of swap being used.
Swap free - The amount of swap left unused.
Network traffic

Outgoing / Incomming
Disk usage

Read / Write to block device (physical drive).
Disk usage

Read / Write to block device (physical drive).