Erase PC data safely and securely

Covering web tracks
Modern web browsers store a myriad of information about an individual's internet use, most of it kept to save time and bandwidth when accessing favourite sites. The code and graphics that make up all the sites recently visited are stored. So when passing on a computer, this is an important point to consider.

For your own use, deleting information is worth doing because it will make the computer more efficient. Neglecting to clean up the browser once in a while can cost a lot of storage space, slow down internet access and make the computer more prone to crashing.

Luckily, Windows has a few simple tools that enable you to clear the browser quickly. Every time a web page is visited, it takes a little while to download all the images on it. These images aren't meant to be stored for a long time because they'd take up too much space, so Windows stores them in a folder called Temporary Internet Files.

This is useful if you're visiting particular sites on a regular basis because already having the images saves on bandwidth. The Temporary Internet Files folder should be cleared out from time to time, though, as it can grow to a surprisingly large size after a long period of internet use.

One of the most pernicious forms of web data storage is the use of cookies. Many websites store small text files on your computer when you view them, and these can be very useful, for storing login information to sites that require registration.

But some cookies also record web viewing habits and send reports back to their owners. It's not quite as cloak-and-dagger as it sounds, because the information is mostly used to target advertising and the means of collecting it is included in the terms and conditions of respectable websites.

However, it may also slow down the browser. Deleting all the cookies is an option, but you will have to re-enter usernames and passwords on sites that require them.

The web page history is another file you might want to remove. When a web address is typed into the browser, it is saved and will appear when you begin to type it into the address window again. Also, when Internet Explorer's History button to the left of the address line is clicked (a circular clock icon with a green arrow pointing backwards), a record of the websites you have viewed will be displayed.

The pages that have been visited are stored in folders filed by date - clicking the links within the folders will take you straight to the page. History can be very convenient for reaching websites that are often visited, but it also provides a list of your web habits to anyone else using the computer.

Internet Explorer can also remember other information that is typed into the browser. A function in Windows called Autocomplete will save particular information you put on forms. Type in the first few letters and suggestions based on previous visits to the web page will drop down. This is designed as a time-saving measure but has the unfortunate side effect of displaying a whole host of personal information.

The big clear-out
When deleting any web information, the first thing to check is that you're not online; there's no point clearing the files if a web page is adding new ones at the same time. Shut down all other programs as well. Open Internet Explorer, go to the Tools menu in the top toolbar and select Internet Options. The new window will display the General tab and this provides the quickest way to delete your data.

In the central box there is a button labelled Delete Files. Click on this, check the box to delete all offline content and click OK. Regular internet users should do this once a month, but if you want to limit the amount of space the folder can use, click on the Settings button in the central panel. You can also specify when the temporary files are updated, but this is best left on automatic setting.

This panel is also useful for editing cookies. On the opening screen of the Internet Options panel is a Delete Cookies button but this dumps the whole file indiscriminately. The View Files button under Settings shows all cookies that are stored on the disk, which then enables you to select which ones to dump.

Removing the record of websites visited is a simple affair. Under the General tab, click the Clear History button. To deal with the Autocomplete function, click on the Content tab in the Internet Options panel. The Autocomplete button opens a window that allows you to delete all form information and passwords, as well as deciding when to switch off the function by clicking Clear Forms.

It's also possible to instruct Internet Explorer not to offer the option of saving passwords. Users of shared PCs who don't want to accidentally save website passwords should ensure that the 'Prompt me to save passwords' box is unchecked.