security code? What is it for?

[amahmood]

I wonder why they want the user to fill a security code field when register in a site like this. They put thess images with distorted numbers.

why should a person want to register in a site for say 10000 times?

I can't even see why a person should register for say 1000 geocities membership. How can they manage them?

[MstrBob]

Those images are for scripts. A lot of times people send scripts, for whatever reason, and may bombard it with new user registrations for anything from spam to trying to knock out the servers or what have you. Those image systems prevent mass user registration.

[amahmood]

Originally posted by MstrBob
Those images are for scripts. A lot of times people send scripts, for whatever reason, and may bombard it with new user registrations for anything from spam to trying to knock out the servers or what have you. Those image systems prevent mass user registration.

How this can knock out the server? There are millions of forms every where on the internet and they don't use a security code. So they are prone to being knocked out?

[MstrBob]

If you were to run a script which sent enough requests at once, it might. Not that these types of things really prevent it. It's more to prevent fraudlent memberships.

[NogDog]

I believe one thing Yahoo tries to prevent is scripts that automatically create a yahoo account with a random name then sends out spam email under that name, and then keeps repeating the process with different names. I know for a fact some people were trying to use the WinRunner test tool and its text recognition capability to circumvent this, which is why Yahoo started using distorted images of the code text so that the recognition software could not decipher it.

[AdamGundry]

If you want to find out more, these are commonly known as "captchas (http://en.wikipedia.org/wiki/Captcha)" or "reverse Turing tests".

Adam

[amahmood]

Thanks for your replies.

they cleared the matter for me.