I need help with verification (captcha)??

I have a directory site and I get about 200 submissions a day but about 90% are aff links and just spam. I was wondering if anyone here new of a simple code to make them verify they are real. I have seen some that make you type "run" in backwards. Im trying to look for it but I cant find it.
Anyone know what this is called or do they have a simple code I can put in??
Thanks

 

www.hotscripts.com

search for "captcha"

there will be tons of free scripts

 

Thanks I will check it out.

 

I write all my directories from scratch using PHP. Here is what I do.

Place this in your form:

<p>Are You Human? -
<?php
srand((double)microtime()*1000000);
$t1 =( rand(1,5));
$t2 =( rand(1,5));
$t3 = $t1 + $t2;
?>

<input name="test1" type="hidden" value="<?php echo $t3; ?>">
<p>
What is <?php echo $t1; ?> + <?php echo $t2; ?>?
<br />
<input name="test2" type="text" size="3" />
</p>

===========================================

Place this in your results page

$test1 = $_POST['test1'];
$test2 = $_POST['test2'];

if($test1 <> $test2){
$verified = 'NO' ;
echo '<h2>Did you make an error in your addition? We use this to foil spam robots.</h2>' ;
}
if($verified <> 'NO'){
print "<h1>ECHO/PRINT YOUR HTML HERE IN PHP FORMAT</h1>";
}

 

scripts like the above (that use common sense/logic questions instead of image verification) also have the advantage of being more accessable to users

 

Thats exactly what I was looking for. Thanks a million...
But I was just trying it and I cant get it to fully work?
You say to "h1>ECHO/PRINT YOUR HTML HERE IN PHP FORMAT</h1>";
"
what html am I supposed to put in there and do I leave the echo/ part in? Or am i missing it completly?
Thanks

 

you'd just put whatever text you want to appear there, between the <h1> and </h1>

 

that beats the hard to read image scripts, but there may be some bots able to fool it... but not likely

Great Script!~

 

bots could only fool it if they specifically have the question/answer already figured out in a database, unless you've got some incredibly sophisticated futuristic AI that you're using to spam stuff with

 

lol, i dont have any AI... i barley have any I.... but ya if the db isnt secure it wouldnt work but that is such a far fetched problem anyway