"Web Form Validation" article on Smashing Magazine

Web Form Validation: Best Practices and Tutorials is my second article on Smashing Magazine. The article explores different methods and approaches in web form validation. It explains the differences between client and server side validation and explains what information should be validated, from required fields to confirmation fields. It emphasizes the importance of good validation feedback and provides several validation techniques that can help you do it properly.

Besides common validation issues it shows some other techniques that might be very useful: help hints, help indicators and the interesting technique called masking/rewriting user's input. It also provides useful information about Captchas. At the end, the article provides a list of useful resources (tutorials, frameworks and plugins) and gives you rules of thumbs in web form validation.

Read the article here