I use Ubuntu because:
- It is easy and user friendly.
- It is virus free (no anti virus is needed)
- I can do all my works with it (office works with office suite, graphics works, listening music, watching video, chatting with friends, browsing internet, running MATLAB etc)
- It is free of cost. I don't have to pay for using Ubuntu (unlike Windows and Mac)
- Maximum softwares in Ubuntu is also free of cost (and there are thousands of softwares).
- It is stable. I don't have to worry about the Blue-Screen-of-Death.
- I can keep my computer running for months without restarting it (and without being hanged)
- The community is very helpful. If I face any problem I simply post that to Ubuntu Forum [1], no matter how stupid the question is, folks over their try to help me out.
"In Linux, can we use applications that can be used in Windows and MAC. For example, is there Linux and Ubuntu of Microsoft Office, Skype, etc."
- If the company releases a Linux version then you can use it on Linux. It entirely depends on the company. As an example, Skype releases their software for linux besides windows and mac, So you can use skype in Ubuntu. So does Google Chrome and Firefox. But MS does not releases any thing for Linux, so MS Office can't be use in Ubuntu. But there is a alternative office suite in Ubuntu which works nice with MS Office. However there is a program called WINE, which can run majority of Windows program to Ubuntu. To see which programs can be run with WINE, go to the WINE database [2].
"Are these OS are reliable for office use even if they are not as useful as Mac and Windows? "
- They are as useful as Mac and Windows. Infact lots of people actually use only linux. Majority of web servers and supercomputers running on Linux. In my university we are using SUSE in our department on more than 1000 client computers. As you can do pretty much every thing with Ubuntu, so you can use it in your office too. But it depends on tastes.
Another thing I've noticed that you are thinking that Linux is an operating system like Ubuntu, Windows or Mac. Actually it is not. Linux is a kernel. A kernel is the core part of an operating system. Kernel of Windows is known as NT, kernel of Mac is known as XNU. Linux is like NT or XNU. Kernel is the fundamental base of every operating system. NT is the fundamental base of Windows XP, Vista and 7. And XNU is the fundamental base of MacOS. Like NT and XNU, Linux is also the base of many Operating systems. Among them Ubuntu is the most popular and widely used.
Unlike NT or XNU, the source code of Linux open. That means you can collect the code, if you have enough knowledge you can alter the code as your need or just for fun, even you can create your own operating system based on that altered code. That's why it is called "Free and Open Source".
There is a myth that you MUST be a geek, to run a Linux based Operating System. Believe me, it's just a myth! Anyone can run and use Ubuntu without knowing a single bit of programming code!