Understanding uname output

What do the various pieces of uname -a output mean? Following is an example output:

Linux mymachine 2.6.18-194.e15PAE #1 SMP Fri Apr 2 15:37:44 EDT 2010 i686 i686 i386 GNU/Linux

I gather that Linux is the O.S, 2.6.18-194.e15PAE is the kernel version. What do the rest of the pieces mean?

Appreciate your help.

In order, the fields are:

• "Linux": The machine's kernel name (e.g, OS).
• "mymachine": The machine's node name (e.g, hostname).
• "2.6.18-194.e15PAE": The kernel version
• "#1 SMP Fri Apr 2 15:37:44 EDT 2010": The kernel version and build time.
• "i686 i686": The processor type and hardware platform.
• "i386": The architecture of the processor. (This and the two above basically all mean the same thing on most systems. They typically only differ on certain embedded platforms.)
• "GNU/Linux": The operating system name.

For comparison, the uname -a from my Mac reads:

• "Darwin" (hardware name)
• "mymachine"
• "Darwin Kernel Version 11.0.0" (version)
• "Sat Jun 18 12:56:35 PDT 2011; root:xnu-1699.22.73~1/RELEASE_X86_64" (build time)
• "x86_64" (processor architecture)
• (The operating system name is omitted by the OS X version of uname for some reason, as are a few other fields.)