Yet another simple intro to LInux Kernel and history of X11 window manager

Linux kernel core is loaded into the directory /boot/vmlinuz-KERNEL-VERSION
additional kernel modules are loaded into /lib/modules/KERNEL-VERSION

all kernel modules can be viewed by using "lsmod" command
kernel modules can be added and removed using "modprobe", you may not remove a module if it is currently in use.
modules have parameters that you can pass to it when it is used. "modinfo" help to view to parameters. the information can also be viewed if you have the kernel source coded loaded into /usr/src
/proc/sys is a directory that contains all kernel core policies. one example is "echo 1 > /proc/sys/net/ipv4/ip_forward" modifies the ip forwarding policy to 1, thus your computer now acts as a gateway, which is useful for many man-in-the-middle attacks for stealing private information.
since linux kernel is open source, you can also modify the kernel policies freely. performance tuning is useful for running programs, such as database. oracle and IBM both provide kernel tuning page to run their database faster on linux. "sysctl -a" is a command that returns all policy documentations for the kernel.

it is very important to know that performance tuning have so many parameters, it is best you know what you're doing before changing the values.

X11 is a graphical transport layer protocol used to abstract linux window managers. this makes it possible for linux to adopt to having many different kinds of window manager without stuck with one came with the distribution. the most pro window manager for linux users is FVWM. It made it possible for linux user themselves to design their own window manager, you can make it look like anything you want, which is also welcomed by most hackers who want to have their own unique desktop style.