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How do I zip and unzip documents?

A partly undone zip

Compressed ’zip’ files are widely used as they pack one or more computer files into a single file or folder which takes up less space. It can be a very useful way of sending or storing files. You’ll need to unzip them to extract the contents inside. Our short guide explains how to do this.

Jack Schofield | 9th September 2010

Zip files are very common on the internet. You can recognise them because they all end with the ‘.zip’ file extension.

What zip does

Zip is an archiving system that packs together one or more computer files into a single file or folder that takes up less space than the originals. If you want to email someone a collection of files, it’s easier to zip them all into one file first. If you want to keep files private, archiving them allows you to encrypt them and add a password to protect them.

Although zip may not be the best archiving system, it’s one that most operating systems know how to handle. The format became ubiquitous in the 1990s thanks to the popularity of the WinZip program, which is now owned by Corel.

How to zip or unzip a file

If you have a zip file and you want Windows XP to unzip it, right-click the file and select ’Extract All’. This should bring up the ’Compressed (zipped) Folders Extraction Wizard’. To extract the file or files, click ‘Next’ and select a directory or folder where the wizard can send the files.

If you want Windows XP to zip a file or a folder, right-click it and choose a ‘Compress’ item. Mac OS X works in much the same way, calling it ‘Archive’ instead of ‘Compress’.

Alternatively, you can right-click inside Windows Explorer, select ‘New’, create a zip file, and give it a suitable name. Next, use your mouse to select the files or folders you want to compress, hold down the left mouse-button, drag the files to your zip file and drop them on top of it. Repeat this as many times as you like - Windows will add the files to your zip file.

You can also use ’drag-and-drop’ to extract files from a compressed folder by dragging them to a different folder or to your desktop. Windows will uncompress them automatically.

Compress to save space

People often compress files to save disk space. Some files can be compressed a lot, and this is true of Microsoft Office’s old Word .doc and PowerPoint .ppt files. (The new Microsoft Office file formats already have zip files inside.)

Some types of file cannot be compressed much more, including MP3 music files and photos in the JPG (jpg) format. Sometimes ’compressed’ folders of these files can be slightly bigger than the originals.

Most people prefer to download a separate archiving program - these are more powerful and easier to use. The free ones for Windows include 7-Zip, PeaZip and IZArc. Most programs, including WinZip, will handle many different archiving formats.

The shareware program WinRAR is efficient and is often used for compressing multimedia files including movies. It can handle the RAR, ZIP, CAB, ARJ, LZH, ACE, TAR, GZip, UUE and ISO formats, amongst others.


Jack Schofield

Jack Schofield

Jack Schofield is a technology journalist and blogger who covered IT for the Guardian from 1983 to 2010. Before specialising in computing, he edited a number of photography magazines and books.