WinZip applications, which create Zip files (.zip or .zipx) allow you to choose between two different compression methods. The Legacy method creates Zip files that are compatible with almost every other Zip file utility, but the compression used is not likely to create the smallest Zip files possible. The Best method alternative uses compression that will create smaller Zip files (usually) with a .zipx extension, but this method may not be compatible with all Zip file utilities.
.Zip Legacy compression (maximum compatibility)
The Legacy (Zip 2.0) compression method uses a traditional data compression algorithm, known as deflate. Deflate is supported by all versions of WinZip and virtually all other Zip file utilities. The deflate method is generally considered to be a good, all-purpose compression algorithm for use with most types of files. .Zip: Legacy compression is your best choice if you will be sharing your Zip file, especially if the Zip utility for the receiver of your shared files is unknown or if that utility is known to use older technology. WinZip applications use the highest setting available for the deflate method, which is maximum deflate. Using WinZip, your .zip files will be easily unzipped and they will be as small as possible for this compression method.
.Zipx Best method (smallest size)
The Best method option allows WinZip applications to choose a compression method for each file from those available in the application. The choice is based on the file type and is usually the method that will compress that type of file the most. .Zipx: Best method should be selected if compressed file size is a primary concern. If you plan to share a .zipx file, please make sure that the receiver of your shared file is using the latest version of WinZip or another Zip file utility that is compatible with all of WinZip's advanced compression methods.
Increased Control - WinZip ribbon interface
With the WinZip ribbon interface (WinZip 14.5 and later) on Windows Vista and later, another level of control is available. In the Settings tab, you can change the compression method WinZip will use when creating either a .zip or .zipx file. These compression method settings will by saved when you close WinZip so that you will not have to make the change again. However, if you want to use a different method you can change settings again.
If you have any questions about this information please email Technical Support.
Default compression - What it is, how to change it
Settings Tab - WinZip Ribbon
Is WinZip compatible with older versions of WinZip and other Zip file utilities?
What registry settings control WinZip's Default Compression?
WinZip Courier Attachment Options