Text in images to prevent bots & spammers

When you sign up for Yahoo (Among many others) you have to enter the
text from a image to protect against automated bots:
http://edit.yahoo.com/config/eval_re...&promo=&.last=

I'm working on a website and would like to use this technique myself.
Does anyone know of any (preferably free) services that can create
these images or help in any way? I think Yahoo used to use a commercial
service, but I'm hoping that as this technique is now so common there
will be lots of choice out there.

Or does anyone know if theres a technical name for this? Part of the
problem is that I have no idea what keywords to use to search for this
on the web :-(

Thanks,
James

In our last episode, James <jimmick@hotmail.com> pronounced to
alt.www.webmaster:

> When you sign up for Yahoo (Among many others) you have to enter the
> text from a image to protect against automated bots:
<snip>
> Or does anyone know if theres a technical name for this?

The term you are looking for is "CAPTCHA" - Completely Automated Public
Turing test to tell Computers and Humans Apart.

--
Mark Parnell
http://clarkecomputers.com.au

"James" <jimmick@hotmail.com> wrote:

> Or does anyone know if theres a technical name for this? Part of the
> problem is that I have no idea what keywords to use to search for this
> on the web :-(

CAPTCHA, do a search on this group as well, to read about the
disadvantages.

I have had several times that I entered the text exactly, and yet, probably
due to some bug, the site kept yelling at me that I got it wrong. (I also
made mistakes in the past, which are now and then easy to make, e.g. some
are case sensitive, others not).

You might lose people because of using it.

--
John Perl SEO tools: http://johnbokma.com/perl/
or have them custom made
Experienced (web) developer: http://castleamber.com/

Thanks, I can now find lots of information. I will read more on this
topic before implementing.

On 23 Oct 2005 19:36:37 -0700, "James" <jimmick@hotmail.com> scrawled:

>Thanks, I can now find lots of information. I will read more on this
>topic before implementing.

Also, be aware that you need a work-around for visually impaired
people and those using text-only browsers. If you check the Yahoo
site, you'll see there's a way to get use email for confirmation.

"James" <jimmick@hotmail.com> wrote:

> Thanks, I can now find lots of information. I will read more on this
> topic before implementing.

Check out how you can quote using Google, otherwise people are going to
complain about that all the time.

Personally I prefer the confirmation link by email a lot. Yes, this can be
automated, and I have no idea how many spammers do so.

--
John Perl SEO tools: http://johnbokma.com/perl/
or have them custom made
Experienced (web) developer: http://castleamber.com/

James wrote

> Thanks, I can now find lots of information. I will read more on this
> topic before implementing.

CAPTCHA is just one system of many, but seems to be used as a generic word
to describe all such systems. It is in fact a trademark.

I believe that someone here also mentioned that there are some bots that
can get around CAPTCHA.

I tend to be of the mindset that you can't block every malicious hit, so
it's better to expect them, and deal with them accordingly.

--
Charles Sweeney
http://CharlesSweeney.com