Opening a password-protected Zip file is a relatively straightforward process -- provided you know the password! It's essentially the same as opening a Zip file that isn't password-protected.
The Difference Between Macs and PCs
When you double-click a Zip file using Apple's OS X Yosemite, you're automatically prompted to enter the password. At that point, the Mac unbundles the contents and copies it to a new file or folder.
Windows 8.1 isn't quite so straight-forward. When you double-click the Zip file, it may appear to open, but it's actually not. Windows is just letting you see the contents. It's only when you try to access a file inside, or when you click the Extract All button, that you are prompted for the password.
Why Does Windows Have the Extra Step?
Giving you a preview without actually unlocking a Zip file can be really useful. Zip files are notorious for containing viruses. This extra step gives you a chance to inspect the contents. If you see a strange file, or one you didn't expect, you can select the files you do want and leave the suspicious file untouched.
Another time when this is beneficial is when you don't need all of the files inside. Just select the files that you do want and drag them to another folder or onto the desktop. When you enter the password, only those files you selected are extracted.
So How Do You Open These Files?
On a Windows PC, double-click the Zip file in File Explorer. Click the Extract All button in the Ribbon to extract everything. To extract only some of the files, Ctrl-click the files you want and then drag them into another folder or onto the desktop. In both cases, you're prompted to enter the password.
On a Mac computer, double-click the Zip file and enter the password.
Anything Else I Should Know?
Zip passwords are case sensitive, regardless of what kind of computer you're using. If you enter the password and get an error, make sure you don't have Caps Lock on.
On both operating systems, unzipping a file creates a copy of the enclosed files and folders, leaving the original Zip file intact. If you don't need the Zip file anymore, you can delete it. Remember, you can also create your own Zip files on a Mac or PC without installing any extra software. Creating an encrypted Zip file in Windows is easy; in fact, you can create a secure password-protected Zip file on any computer.
Final Note: Password protected Zip files are not 100 percent secure. Even if you don't know the password, there are ways to crack a zip file open.