Computers: Some free advice on verbal abuse: Giveaway software may seem like a good deal, but you may get more - or less - than you bargained for. David Hewson reports

The most abused word in the English language has four letters and begins with 'f'. The very idea that something is 'free' is contrary to the laws of nature - it may be free to you, but someone surely paid for it - and in the wonderful world of personal computers, the only thing you are likely to get that is truly free is a virus.

Yet there is a large and odd industry out there based around the idea of 'free' software. It fuels pages of rather grotty adverts in certain computing magazines and fills up megabytes of space on electronic bazaars like the Compuserve network. Computer magazines stick 'free' disks on their covers and find their sales shoot through the roof. An enterprising soul has even started a subscription service for 'free' software - pay a small monthly fee and he will send you diskfulls. Can it all be bad?

Well, not all, just most. The software you find bandied around through magazine cover mounts and specialist suppliers breaks down into two categories - 'freeware' and 'shareware'.

Freeware is genuinely free; you can use it and pass it on to your friends without being expected to pay anything in return. Shareware is software that costs you nothing to acquire but, if you use it regularly, you are honour bound to send the designers something for their efforts; sometimes pounds 50 or so.

Once upon a time shareware designers used to make their point by inserting pathetic little reminders asking for money into information screens in the program. Nowadays they are smarter and will often write a routine into the application that puts a time bomb inside it; if you have not registered in 30 days it simply refuses to work any more.

The trouble with freeware and shareware is that they are invariably the product of small designers who do not have the resources available to commercial software companies. All software has bugs, even the stuff from the billion-dollar people which has been put through the wringer by testers worldwide for months before release. Shareware programs can contain bugs so large that they merit the attention of the public health department.

Commercial programs fall over and damage your work; shareware can, on occasion, take big chunks out of your hard disk that will never come back. It is not all like this, of course. There are freebies around that are worth having and it is useful to be able to try something before you pay for it.

But the good is vastly outweighed by the poor, particularly in the PC Windows field which is shot through with junk, and junk, moreover, that sometimes does things to your Windows system even the most hardened buff cannot understand.

Shareware works best in providing little utilities and - in Macintosh jargon - desk accessories and 'Inits' that add bells and whistles to your operating system, making it easier to find and launch files, for example, or to compress data.

Several of these blossomed gloriously on the Mac a few years ago and were eventually paid the ultimate compliment - they made the jump from shareware to commercial software. Others live in a kind of halfway house, such as the organiser software First Things First, which can be downloaded from Compuserve and bought over the telephone with a credit card for about dollars 40 ( pounds 26).

The trouble with utilities is that they usually work by gobbling up a chunk of PC memory and sitting there all the time waiting for something to do - TSRs, terminate and stay resident programs, in the jargon. This can be an inefficient use of main memory and is also the source of a lot of crashes.

By far the worst freebie software is the stuff that claims to be full-size working alternatives to conventional, commercial mainstream applications. A few years back, when the stuff of personal computing life such as word processors and accounts packages cost several hundred pounds a throw, there was an argument for using shareware.

Nowadays you can pick up excellent mainstream packages, with long pedigrees, customer support and good, regular upgrades, for under pounds 100, or get them bundled with your new machine. If your needs are basic indeed, and your machine is an ancient pre-Windows model, then a shareware word processor may fulfil them; but don't go in there with high expectations.

But the idea of 'try before you buy' software is attractive and could catch on. It is quite simple for companies to place demo versions of software on CD-rom, let you play with them and, if you like what you see, give you a code number in return for a credit card payment. You type in the code, the demo version turns into the real thing and the manuals come through the post the following day. The company behind this idea, Instant Access, sells its first CD for pounds 9.95, with 200 real applications on it, and will be offering a Windows version soon.

The trouble is that the software business revolves around the distinctly shaky notion that all of us actually need more of the stuff than we have already got. The average personal user probably requires a word processor, something to handle money, something that organises names, addresses and appointments and a few toys such as games and drawing programs. Beyond that, you are just filling up your hard disk with drivel and expensive drivel at that, since the real cost of software goes well beyond the package itself; add in your time, the extra disk space and memory you need, and even free software may not be so cheap.

The lure of all software is that a better program means better work. Your novel going shakily in Word for Windows? Switch to Ami Pro and you will fly through it in no time. But this is patent nonsense, peddled by journalists (like me) who get the stuff for free - and we are just software junkies who should know better and privately do.