Creating a CAPTCHA with PHP - How does a CAPTCHA work?
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To put it simply a captcha works by generating a random string, writing it to an image, then storing the string inside of a session or cookie or by some other method. This is then checked when the form or operation is performed. Below is a step by step layout of how it works. 1. Random text generated 2. Text written to image 3. Text stored in session/cookie/database 4. Image displayed to user 5. User enters the code 6. User entered code is checked against the stored key 7. If they match then something is done
On the next page I will show you how to generate the random text to be used later on in the script.
Next: Creating the random text >>
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