At a party you meet a bewitching stranger and ask them what they do. Avoiding eye contact, the stranger mumbles something about working in IT before eventually confessing: 'Uh, I design scumware.' Do you a) pelt them to death with canapes? b) quickly move on to someone else in a profession with a better reputation - a loan shark for instance? or c) respond: 'Wow, cool! Would you like to come back home with me?' If you chose the last option you are, by common consent, one sick puppy. After all, in the digital pantheon, the scumware set are widely seen as up there with virus makers and spammers intent on converting the world to Viagra. In the eyes of their detractors, scumware makers deserve to be strapped in front of a screen displaying a web page sporting a busy background graphic, blinking text and an automated slide show featuring banal animation (dancing hamsters, say) for the rest of their natural lives. So what is scumware? Macintosh mavens and Linux lovers may assume it is just another derogatory term for Microsoft Windows software. In fact, scumware means a particularly rude and obnoxious form of software that has the nerve to alter the origin of links on a web page without the knowledge or consent of the site's owner. As a result of scumware antics, the poor klutz who clicks on the link is whisked to a page they never intended to visit. Worse, the page in question is unlikely to be relevant or spiritually uplifting - think gambling and pornography. This means that, one second, the scumware victim is innocently gazing at a site devoted to the appreciation of cute, cuddly toy rabbits. The next, courtesy of a rogue link on the word 'love', he has been hijacked and shunted to a site sweetly entitled, say, Cheerleader GynoCam. A prime culprit is eZula's TopText, which comes bundled (concealed) with the Napster clone Kazaa. Like Microsoft's dearly loathed SmartTags, TopText works through your browser, inserting advertisers' hyperlinks in its pages. Other software products that steal traffic by sneakily adding linking options to a site include: Surf+ , Gator - which boasts that it allows you to advertise even on sites that shun advertising - and Melting Point. For the webmaster, scumware means lost visitors, sales and commissions. To the victim, if the victim realises what has happened, it means experiencing a sense of violation and feeling anger towards the lowly form of pond life responsible. Scumware.com, a website devoted to eradicating the plague, calls the stealing of traffic from independent websites 'the biggest threat to the survival of the Internet to date' and offers advice on the fine art of 'descumming' your computer. A purgatory program it recommends and which is valuable for removing unwanted non-viral visitors in general is LavaSoft's Ad-aware. But Ad-aware only offers partial deliverance. Cleaning out the scum completely is a complex process you may prefer to skimp unless you have obsessive-compulsive tendencies. If you do, have a good twitch and then follow scumware.com's instructions. Or just learn to live dangerously. Like the offline world, the digital domain has its fair share of bugbears that defy the slick, sleek image every dotcom strives to project. To be ridiculously generous, scumware's vile machinations may serve a purpose. They lend the generally rather sterile purlieus of cyberspace an edge and make our exploration more interesting. Do we want the Internet to be as pure as filtered water? A sprinkling of scum adds so much texture and colour.