No need to send them to another page. Data validation is easy to do.

1) Receive the POSTed form data (top of the file)
2) Validate it. Put errors into an array so you can echo them out later
3) Check to see if you found any errors. If not, do whatever you want to do with the data.
4) If there are error, redisplay the page and list the errors so the users knows what they did wrong.

This method also allows you to repopulate the form fields if there is an error so they don't have to type it in again.

Another idea is to also include a javascript validation. There are plenty of tutorials found through google. Just look up "Javascript Form Validation".

That way when the button is clicked, the form is instantly checked and a message displayed at that moment without a page having to be reloaded.

However, you still should included some server side validation, using php. The javascript is jut to make it easier for the person. The php is there incase the person gets around the javascript.

No need to send them to another page. Data validation is easy to do.

1) Receive the POSTed form data (top of the file)
2) Validate it. Put errors into an array so you can echo them out later
3) Check to see if you found any errors. If not, do whatever you want to do with the data.
4) If there are error, redisplay the page and list the errors so the users knows what they did wrong.

This method also allows you to repopulate the form fields if there is an error so they don't have to type it in again.

Don't forget to sanitize and validate the data. You didn't say if you are storing in DB or emailing, but the PHP mail() function can be used by spammers if you're not careful with your data.

http://www.securephpwiki.com/index.php/Email_Injection