One of the most common programming scripts on the web today is to check what the user enters in a web form, before it is sent out through the Internet to it srecipient server that will process it. If, for example, you are entering credit card information, a validation program will check your entries upon completion (when the Submit button is clicked).It will check for extraneous information, such as typing alpha characters instead of numbers or if a text box requiring information was left empty.
The purpose of this validation is to prevent the data from reaching the server that will process the information and then find out that some of the information is wrong. In this case, time was wasted. If the problem is found before the data is sent out, or in technical terms, before the data leaves the client machine (your computer), much time is saved and the user can make the correction immediately.
A typical PC motherboard controls the logic behind all programming languages
Let’s take an interactive look at what a validation script will do if inappropriate or missing information is entered.
Scenario: You have a web form that requires certain information. You enter the information, then click Submit. See what happens if you click Submit without entering any information.