Web forms in online shops, forums and guestbooks are often targets of Spam. You can protect yourself from unsolicited comments by using CAPTCHAs on your website. Along with commercial solutions, you will find many free CAPTCHA services on the Internet, such as captchas.net. Another free and easy to use service is reCAPTCHA.
On http://recaptcha.net you get a free key for using the service on your website. In order to use reCAPTCHA, you need a public/private API key pair. This key pair helps to prevent an attack where somebody hosts a reCAPTCHA on their website, collects answers from their visitors and submits the answers to your site.
To use reCAPTCHA, you only have to add a few lines of code to your website. For detailed instructions on using reCAPTCHA please visit reCAPTCHA’s website.
Captcha’s zijn eigenlijk niet zo’n goed idee. Sommige spambots kunnen ze al lezen. Sommige mensen kunnen ze niet lezen.
Ze zijn dus ongebruiksvriendelijk en falen in hun doel.
Trouwens is spam het probleem van de gebruiker? Neen, dat is het probleem van de beheerder van de website.
Meer info hierover kan je hier vinden:
Captcha kost je geld
great reaaaaaad thank you so much =]
As these types of captcha services are being attacked by automated commenting services, sometimes a simple custom one may be much harder to crack