Compressed file formats?
Q
In Issue 534’s Problems Solved (page 67) fellow reader Edmund Hobby asked what software he needed to decompress a ZIP file he’d downloaded. I know Windows has this ability built in, but you also said that other compression types and programs exist. That got me wondering about the difference, and why you would pay for compression programs? Anna Denmark
A
Let’s start by imagining your questions are about, say, an office suite like Libreoffice. It doesn’t come with Windows but Libreoffice is free and handles Office documents, so why does Microsoft Office exist – and why would anyone pay for it?
The answers are many but boil down to this: different companies produce different products to serve different needs, and appeal to different customers. For example, Microsoft Word has better image-handling and text-flow tools than Libreoffice Writer; but Writer has more refined dictionary and grammarcorrection than Office. Anyone creating image-heavy documents, then, would be better served by Word, but for simple jobs Writer might be preferable.
Returning to compression, the ZIP format was invented in the late 1980s by a chap call Phil Katz. By 2001, his creation was so popular that Microsoft built support for it into Windows XP. That support remains today.
But ZIP isn’t necessarily the best. A decade later another developer, called Igor Pavlov, came up with 7-Zip and the associated 7Z file format. Compared like for like this typically produces smaller compressed files than the ZIP format, but it is slower. The 7-Zip program that makes these is a free download, from www.7-zip.org. It also handles ZIP files, and offers features not available in Windows – such as the ability to add passwords to compressed files (see screenshot).
That brings us to paid-for compression programs. The best-known is probably Winzip ( www.winzip.com). Why would you ever pay? For endless bells and whistles, basically. At heart Winzip is just another way to compress files, but it handles loads of formats, and offers sharing features and integration with online-storage services like Dropbox and Onedrive.
Few people need to pay for compression software but Winzip is up to its 22nd version, so clearly there’s a sufficient number of advanced users who consider it worthwhile.
What to know the difference between technical terms? Email noproblem@ computeractive.co.uk