Key Down and Key Up receive the key code corresponding to the key that was pressed.

This allows you to determine if special keys such as Shift or Control and F1 were pressed.

Validating and Validated are only fired if the control that receives focus has the Causes Validation property set to true.

The reason why it's the receiving control that fires the event is that there are times where you do not want to validate the control, even if focus changes.

This tutorial helps you to understand how you can use Data Annotation attributes for validation of model data. Various Data Annotation attributes gives you a simple way to perform validation on model data. NET MVC Model binding tutorial which gives you a basic mvc application with simple model binding. Replace the code from Customer model with below attributes and properties.

All Data Annotation attributes are included in System. These attributes are helpful for common validation pattern like Required, Range, String Length etc. You can also Download source code of previous step for basic application. Here you have use Required for Customer ID, String Length for Company Name, Range for Age, Data Type for Join Date, Regular Expression for Email and Enum Data Type for Customer Type validation and provided Error Message for each validation attribute.

These six events occur in the order they are listed here.

They are known as "Focus Events" and are fired whenever a controls focus changes, with two exceptions.

When a control that has this property set to true is about to receive focus, two events are fired: Validating and Validated. A value indicating if the Text Box changes the case of the text entered.

You can handle these events in order to validate data in the control that is losing focus. The possible values are: q Lower: All text entered into the text box is converted lower case. q Upper: All text entered into the text box is converted to upper case. If this value is set to be larger than the total number of characters in the text, it is reset by the control to be the total number of characters minus the value of Selection Start.

There are others as well - see the Wikipedia page on histograms.