what is the function of unix and linux ?and how can i use it?what are there adventages and disadventages?
Unix and Linux, like Windows, are operating systems. Mostly designed for server machines, they have seen a lot of development as desktop/end user operating systems. Basically, they run your computer and provide function for applications like Web Browsers, Word Processing, whatever it is that you seek to use on your computer.
I'm a bit light on the differences between Unix and Linux. Unix tends to cost, usually a fair amount, although there are free versions. Linux is free, although some companies have bundled applications and support into a package that they sell for a fee. I'll leave it at that.