I've downloaded a "zip" file - what now?
Files which end in ".zip" are called zip files (unsurprisingly!). A zip file is a container for other files of any sort (Word documents, Powerpoint slides, etc), which is useful because it means you only have to download one file, instead of many. The most useful thing about zip files though is that it compresses the files inside it, which means that the one zip file will be a smaller file to download.
If the file you've downloaded is a zip file and you can't open it, don't worry! There is a free utility called 7-Zip which can open and "extract" the files from inside a zip file for you. You can download it for free here: http://downloads.sourceforge.net/sevenzip/7z457.exe.
Another common program which opens zip files is called WinZip. Technically, WinZip is not free software - it does offer an "evaluation" version which will work fine, however it will most likely show you a "nag" screen asking you to buy it. If you read closely, you should be able to see a button to "continue using evaluation" or something similar. If you really like WinZip, you should buy it, but here at SummitZero, we recommend 7-Zip. :)