This file contains information about the system load. The first three numbers represent the number of active tasks on the system - processes that are actually running - averaged over the last 1, 5, and 15 minutes. The next entry shows the instantaneous current number of runnable tasks - processes that are currently scheduled to run rather than being blocked in a system call - and the total number of processes on the system. The final entry is the process ID of the process that most recently ran.

Example output:

0.55 0.47 0.43 1/210 12437


How are these load numbers useful? Typical uses? Typical values and what they indicate about a system's state?
And especially, in the context of a (shared/virtual hosting) Web server, what can /proc/loadavg tell me?

Thanks ;o)

You're typically reading these number via uptime(1) linux command. The bigger the numbers, your server is more loaded. Typically, a server with 4 cores is not loaded if loadavg is below 4. But, if your load is primarily I/O bound, numbers can get quite big, although CPU is mostly idle. In that case you need to use other tools to assess I/O load.