Rules / Validations for Web Forms


As a developer, what rules / validations do you follow for your web forms to maintain a standard on the internet. For example, Firstname or lastname should not be more than 64 chars, should not contain numbers or special chars etc etc.

Do you have a compiled list of all rules that needs to be followed on all forms across your application?

I am looking for a list of such rules that is globally accepted.

Thanks for any inputs.