Download the JRE (java runtime environment) from Sun's website. make sure you get a version that will run on your os.
Ubuntu can be installed on a Mac or run from a LiveCD (See links below). It can be run on a virtual machine on top of Mac OS X.
Juniperext.exe is an extension of ActiveX and Java software packages on the Windows OS. It is the program through which Java functions are executed on a browser.
yes it is built in.
You could install an operating system using a memory stick and a free program from microsoft called windows 7 usb installation tool (will work for any iso file). Or you can run the OS inside another OS. For example you could run Ubuntu inside Windows 7. using a program called virtual box, which is also free.
You can run a program in any OS. For example an executable program can be run in windows by .exe file extension.
One version of a program will work on all major OS'. Business uses it because it's more secure i believe.
Linux.
You could easily download Chrome for Ubuntu OS. It is available on the Chrome website as well.
If you are starting and new to Linux try Zorin OS. If you are experienced and know more about and how to use Linux the get Ubuntu.
Platform independent language means once compiled you can execute the program on any platform (OS). Java is platform independent. Because the Java compiler converts the source code to bytecode, which is Intermidiate Language. Bytecode can be executed on any platform (OS) using JVM( Java Virtual Machine).
i am usinf linux ubuntu OS, i want to simulation and synthesis steps in xilinx vivado...please help me
Ubuntu is a Linux distribution (as in a specific OS setup with the Linux kernel.)