I presented the other day a simple way to implement a CAPTCHA user control in ASP.NET Webforms, in order to also illustrate a generic image handler (ashx) and help others better understand the HTTP protocol and the process of loading a web page.

I am posting here the slides and the code.

WebCaptcha-slides-english.zip (1.01 mb)

WebCaptcha-slides-romanian.ro.zip (1.01 mb)

WebformsCaptcha - code.zip (291.92 kb)