Many people search for apps/software such as this because Windows doesn't come with a file-unzipping function that allows them to open and/or use RAR files. The Winrar 64Bit program does allow you to unzip and zip RAR files.
It means that your multi-core device is able to make the program run a little faster. Since most people have a modern computer, then most people are going to need/prefer the 64Bit version.
It is not free. You are able to download the software and install it, but you are only allowed to use it for free for a short while, after which your trial is over and you either have to uninstall the software or pay to keep using it.
It works on Windows 7, 8, 8.1 and 10. If you have another operating system, then you should look online because there are other versions and altered semi-official version that work for other operating systems and Windows iterations.
It offers complete support for ZIP archives and RAR archives, but it is also able to unpack CAB, LZH, ARJ, TAR, ACE, GZ, UUE, JAR, BZ2, ISO, XZ, 7Z, and Z archives.
Some unzipping facilities only work on your right-click menu. The Windows ZIP file unzipper only works on right-click menus. Winrar 64Bit is actually a tool that has a GUI and a subtle smattering of other functions too.
Winrar 64Bit is able to archive your files with ZIP or RAR, but some version of the archive files you create may only be unzipped with Winrar 64Bit, ergo you may be unable to unzip such files with another device if it doesn't have this software.
You do get a limited number of extra features when you pay for the software. You get the full version of the software when you pay for it, so you also get things such as self-extracting files and multi-volume archives.
It is very unlikely that you will ever need to buy an extension or add-on to this program unless a brand new and original method for file archiving is created. Even in that scenario, the developers of this program are most probably likely to update the tool rather than build an extension or add-on.
WinRAR is able to support archives and files of as much as 8,589 billion gigabytes in size. If you are simply looking for archiving functions, then there is no limit to how many files that this program may archive. There is no limit to the size of a file that this program is able to archive.