Entering "cat /proc/meminfo" at a command line will reveal everything
important the kernel knows about memory and swap.

Similarly, "cat /proc/cpuinfo" for the CPU(s), "cat /proc/version"
for the kernel info including what compiler was used to build it, etc.

There's a bunch of "files" (and "directories" containing "files) in
/proc that can be simply typed out (via "cat") for information. "files"
and "directories" are in quotes because /proc is a virtual filesystem.