While working with your computer you surely have come across files in the .zip or .rar format. These are so called packed or compressed files, their function is to store multiple files and/or folders into one single file and compress them so they are easier to send and waste less space. Windows has a built-in function to pack and unpack files: to compress files, just right-click them and select Send to > Compressed (zipped) folder. To uncompress, right-click the zipped file, select Extract all... and choose a directory where to put the uncompressed folder. However there is a more powerful tool called WinRar which is easy to handle, has a bunch of useful functions and also supports another compressing format, .rar which is safer than zipped compression if provided with a password. WinRar is downloadable for free as a 30-day trial version and reminds you to buy the full version after 30 days but is still usable then. You can download the appropriate version for your system here:
Double-click the downloaded file and click Install on the appearing window. The next window displays WinRar's configuration. The checkbox-filled panel on the left determines which formats your computer is supposed to open with WinRar. Usually all predefined settings should be alright, so click on OK.
On the next screen, click on Done to finish installation. Nearly all compressed files are now being associated with WinRar and have adopted its icon:
Uncompress files associated with WinRar by double-clicking them and drag-and-dropping its content anywhere on the screen or clicking on Extract To and choosing the target directory.
To compress files, just select the ones you want, right-click them and choose to either compress them to a .rar archive immediately or to add them to another archive (.zip or whatever you want) with more detailed options.