What is Linux ?

 Miss Manali Shirish Magdum
B.E.(computer Science & Engg)
Red Hat Certified Engineer (RHCE)(RHEL 5)

 Red Hat Linux is an open source, multitasking operating system, featuring outstanding reliability and flexibility.Now we will see the fundamental difference between Linux and Windows 

1: Full access vs. no access
Having access to the source code is probably the single most significant difference between Linux and Windows. The fact that Linux belongs to the GNU Public License ensures that users (of all sorts) can access (and alter) the code to the very kernel that serves as the foundation of the Linux operating system Unless you are a member of a very select (and elite, to many) group, you will never access code making up the Windows operating system. 

2: Licensing freedom vs. licensing restrictions

 Along with access comes the difference between the licenses. With a Linux GPL-licensed operating system, you are free to modify that software and use and even republish or sell it (so long as you make the code available). Also, with the GPL, you can download a single copy of a Linux distribution (or application) and install it on as many machines as you like. With the Microsoft license, you can do none of the above. You are bound to the number of licenses you purchase, so if you purchase 10 licenses, you can legally install that operating system (or application) on only 10 machines.

 3: Online peer support vs. paid help-desk support

  With Linux, you have the support of a huge community via forums, online search, and plenty of dedicated Web sites. And of course, if you feel the need, you can purchase support contracts from some of the bigger Linux companies (Red Hat and Novell for instance).
On the other side of the coin is support for Windows. Yes, you can go the same route with Microsoft and depend upon your peers for solutions. There are just as many help sites/lists/forums for Windows as there are for Linux. And you can purchase support from Microsoft itself.

 4: Command line vs. no command line

 The command line will always be an invaluable tool for administration purposes. Nothing will ever replace  text-based editor, ssh, and any given command-line tool. I can’t imagine administering a Linux machine without the command line. But for the end user  not so much. You could use a Linux machine for years and never touch the command line. Same with Windows. You can still use the command line with Windows, but not nearly to the extent as with Linux. And Microsoft tends to obfuscate the command prompt from users. Without going to Run and entering cmd (or command, or whichever it is these days), the user won’t even know the command-line tool exists.

5: Centralized vs. noncentralized application installation

With Linux you have (with nearly every distribution) a centralized location where you can search for, add, or remove software.. With Synaptic, you can open up one tool, search for an application (or group of applications), and install that application without having to do any Web searching (or purchasing).
Windows has nothing like this. With Windows, you must know where to find the software you want to install, download the software (or put the CD into your machine), and run setup.exe or install.exe with a simple double-click.. Installation under Linux is simple, painless, and centralized.

 6: Flexibility vs. rigidity

 I always compare Linux (especially the desktop) and Windows to a room where the floor and ceiling are either movable or not. With Linux, you have a room where the floor and ceiling can be raised or lowered, at will, as high or low as you want to make them. With Windows, that floor and ceiling are immovable. You can’t go further than Microsoft has deemed it necessary to go.
Take, for instance, the desktop. Unless you are willing to pay for and install a third-party application that can alter the desktop appearance, with Windows you are stuck with what Microsoft has declared is the ideal desktop for you. With Linux, you can pretty much make your desktop look and feel exactly how you want/need. You can have as much or as little on your desktop as you want

 7: Automated vs. nonautomated removable media

 I remember the days of old when you had to mount your floppy to use it and unmount it to remove it. Well, those times are drawing to a close — but not completely. One issue that plagues new Linux users is how removable media is used. The idea of having to manually “mount” a CD drive to access the contents of a CD is completely foreign to new users. There is a reason this is the way it is. Because Linux has always been a multiuser platform, it was thought that forcing a user to mount a media to use it would keep the user’s files from being overwritten by another user.

 8: Multilayered run levels vs. a single-layered run level

You can work from either the command line (run level 3) or the GUI (run level 5). This can really save your socks when X Windows is fubared and you need to figure out the problem. You can do this by booting into run level 3, logging in as root, and finding/fixing the problem.
With Windows, you’re lucky to get to a command line via safe mode — and then you may or may not have the tools you need to fix the problem. In Linux, even in run level 3, you can still get and install a tool to help you out (hello apt-get install APPLICATION via the command line). Having different run levels is helpful in another way. Say the machine in question is a Web or mail server. You want to give it all the memory you have, so you don’t want the machine to boot into run level 5. However, there are times when you do want the GUI for administrative purposes (even though you can fully administer a Linux server from the command line). Because you can run the startx command from the command line at run level 3, you can still start up X Windows and have your GUI as well. With Windows, you are stuck at the Graphical run level unless you hit a serious problem.
These are the fundamental differences in Linux  and Windows.