What on earth is a “captcha”?

By | May 1, 2010
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In the Computers newsletter this month:

  • What on earth is a “captcha”?
  • The registry cleaner that’s not a con
  • A recommended website
  • The latest version of a popular way to cure PC problems


This issue I’ll decode another piece of computer jargon, tell you where to get a free program that just might speed up your PC and pass on a website a reader recommended to me the other day.

What on earth is a “captcha”?

Every so often when you’re using the web, a webpage will ask you to type in a series of letters and numbers that it’s displaying.  The letters and numbers will look slight odd, or distorted and usually have strange background.

It seems like one more thing to make using the PC harder. But here’s why they do it:

Spammers write programs to automatically scour the web and find places they can leave notes promoting their dodgy products.  They can’t get into things that are password protected but if there’s a webpage open to everyone, they can get in to that.

So the website owner needs a way to stop it – or the spammer’s automatic program will fill up their webpage with junk comments.

Another reason for them is on important password protected websites – you could write a program to try all the passwords it could possibly be – starting with aaaaaaaa, then aaaaaaab and so on.  For a computer, it wouldn’t take too long and eventually it would get in.

Some websites have a “lock-out” facility where if you (or a program) get the password wrong three times in a row, you can’t try again for an hour or a day.

But others use “captcha”s.

Since the text is all distorted and on a strange background, a computer program can’t work out what it says.  But a human can – so only a human can type in what it says.

So although they’re a bit of a pain, they do keep the web a safer place.

I still think it’s a silly name, though!

Oh, and if you have trouble reading one, you can usually click to get another that might be easier to read.  Or click to have it read out to you – again, automatic programs won’t be able to recognise the letters when they’re read out, but a human can.

The registry cleaner that’s not a con

The registry is a part of Windows that keeps track of what programs you have, what they all do, how the interact and so on.  Over time it can get cluttered up with information about programs you don’t have any more and so on… and that can slow your PC down.

Hunting these bits down by hand takes a lot of time and confidence, so there are programs to do it for you.

But there’s a snag.

Most of them proclaim loudly that they’re free.  And they are – up to a point.  They’ll scan the registry for you and tell you how many things they’ve found that need fixing (usually lots) but if you want them fixed, you’ll have to pay.

Some of them will fix it if you then pay – but one or two won’t.  In fact one or two make up the list in the first place, then afterwards just say it’s fixed without doing anything.

But even the ones that do fix it are a bit of a con – since they said they were free but you have to pay for them.

Others are more up front about it, admitting you have to pay from the start and at least that’s fairer and more honest.  But you still have to pay for a program you won’t use very often.

Luckily there’s one good one that’s completely free – called Ccleaner.  You can get it from here. It does ask if you’d like to make a donation (which is how they can make it free) but you don’t have to, it’s up to you.  With programs like this I always take the approach that I’ll try it and see if it helps, and if I find it useful I’ll make a donation – but if it’s no use I haven’t spent anything on it.

You download it, install it, then click on Registry on the left and scan on the right.  Then once it’s done, click on Fix selected issues.

I normally only recommend using a registry cleaner if you’ve noticed your PC running slowly or if there’s some problem it’s having.  But if that happens to you, Ccleaner is the one I’d recommend.

A recommended website

A reader recently recommended this website , called Silverhairs which he thought some of you might find useful too.  I’ve had a look and it has some useful information on it – well worth a look.

Help! My Taskbar Vanished – now updated (2nd Edition)

Just to let everyone know we’ve recently updated Help! My Taskbar’s Vanished to create the 2nd Edition.  It’s a book covering 132 possible problems that commonly happen to PCs (including your taskbar vanishing) – and what to do about them.  I’ve made sure it now covers Windows 7 (which wasn’t out when I first wrote it) but also checked everything else to make sure it’s up to date and still relevant.

If you don’t already have it, you can read a bit more and (if you like) get hold of a copy on our usual free trial by clicking here.

That’s all for this time – I’m off to make the most of the bank holiday – I hope we get some sunshine!


Tim Wakeling

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