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In the simplest sense, the purpose is to experience a new place of the world.  It can provide some amazing new perspectives and learning opportunities.
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Sure.  Physical fitness is important for people of all ages.  Kids love to run around and play.  You don't necessarily need a gym for this but it will help them develop skills and interact with other kids.  They also usually have great equipment for them to play on as well.
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Each operating system implements a "virtual machine" software which runs the JAVA programming language.  Hence, a programmer only needs to code in the one language to be able to run on all the operating system platforms that implemented the JAVA virtual machine.
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Computers have saved the banking industry millions and millions of dollars.  It ultimately allows for greater efficiencies by enabling the banks to phase out legacy "paper" processes for streamlined computerized processes through customized software programming.  The "Check 21" initiative will save hundreds of millions of dollars a day by eliminated paper check transfers.