Requirements analysis<span>, also called </span>requirements<span> engineering, is the process of determining user expectations for a new or modified product. These features, called</span>requirements<span>, must be quantifiable, relevant and detailed. In software engineering, such </span>requirements<span> are often called functional specifications. i hope this helps
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The hypervisor which works on older PC's without hardware virtualization support is called VirtualBox. It is a software allows you to run operating systems in special environment which is called virtual machine. It means that you can run another OS without re-installing existing one.