Client-side validation occurs before form submission and can improve the user experience but is not secure as validation is done in the browser. Server-side validation is needed for true security as it validates in PHP code after submission but is slower. Using both provides a good balance of convenience and security but requires the most programming effort.

1. For Client vs. server-side
validation
By
Dr. mousumi dhara

2. client
• Validation can be performed:
– client-side (beforethe form is submitted)
• can lead to a better user experience,but notsecure
(whynot?)
– server-side (in PHP code, after the form is submitted)
• needed for truly secure validation,butslower
– both
– best mix of convenience and security, but requires most effort to program