Mac : Install High Sierra in Dual Boot

The Mac OS High Sierra can be installed and dual boot along with a constant release of Mac Operating System, EI Capitan, Sierra, or another OS X release of Mac.

It is one of the best options for beta testers, developers, and pro users who like to try the new Mac Os 10.13 beta let go without assigning to it as it authorizes the primary stable Mac OS release together on the same processor and does not overwrite it. After finishing, you are allowed to boot between the stable Mac OS release and the beta MacOS High-Sierra release.
The new macOS 10.13 High-Sierra comes with new and fresh features are the best and you can expect more promising functions. But, if you are still hung up with macOS10.12 Sierra, then you can choose to install 2-Operating Systems execute in contrast, or probably you need to run apps on both operating systems. The reason could be anything, and you will have to perform a Mac dual boot.
Ready to install the 2-operating system on a single hard drive, and before you try to manage between macOS High Sierra and macOS Sierra, you might have to make some preparations consequently to store your present data safely and generate the required space. Here is how you need to do.
Back up your Mac: You must have a back up of your Mac as the dual booting involves emptying your startup disk, and it is needed to store all your data safely. You can as well backup files, apps, and documents manually by copying everything to an external drive and iCloud. Storing in iCloud is the most secure way as it selects Apple’s own software.
Clean up your drive: Running 2-Operating Systems at a time can increase the disk space demands. That is why a complete system cleanup is the best way and it is the best step to follow. You must clean up everything, including all your old baggage that prowls your Mac’s memory. Remove all the leftover applications, system junk, and a lot of temporary files. To do this job, you need to download CleanMy Mac app, and this app will perform automatic cleanup in just a matter of time. According to the app developers, this app can remove old junk from your system and allows you to get a lot of free space so that you can operate two operating systems on your Mac system.
Create a second separation on your hard drive: To produce a new division on your Mac, you have to open DU (Disk Utility)and choose the hard drive that comes with main operating system partition. You just need to press the Partition tab, and now you can create an additional partition, and designate and name its size. The macOS High-Sierra needs around 8GB of space ensure to preserve at least around 20GB that is needed for a regular-working partition. Once you agree with the specification, and then press Apply. You should know that the new partition takes some time before it installs and ready to available for use.