How to use <apex:inputTextarea>  in Visualforce Page?

<apex:inputTextarea> :
A text area input element. Use this component to get user input for a controller method that does not correspond to a field on a Salesforce object, for a value that requires a text area. 

This tag supports following attributes:

attribute	Description
accesskey	The keyboard access key that puts the text area in focus. When the text area is in focus, a user can enter a value.
cols	The width of the field, as expressed by the number of characters that can display in a single row at a time.
dir	The direction in which the generated HTML component should be read. Possible values include "RTL" (right to left) or "LTR" (left to right).
disabled	A Boolean value that specifies whether this text area should be displayed in a disabled state. If set to true, the text area appears disabled. If not specified, this value defaults to false.
id	An identifier that allows the checkbox component to be referenced by other components in the page.
label	A text value that allows to display a label next to the control and reference the control in the error message
lang	The base language for the generated HTML output, for example, "en" or "en-US".
onblur	The JavaScript invoked if the onblur event occurs that is, if the focus moves off of the text area.
onchange	The JavaScript invoked if the onchange event occurs that is, if the user changes the content of the text area.
onclick	The JavaScript invoked if the onclick event occurs that is, if the user clicks the text area.
ondblclick	The JavaScript invoked if the ondblclick event occurs that is, if the user clicks the text area twice.
onfocus	The JavaScript invoked if the onfocus event occurs that is, if the focus is on the text area.
onkeydown	The JavaScript invoked if the onkeydown event occurs that is, if the user presses a keyboard key.
onkeypress	The JavaScript invoked if the onkeypress event occurs that is, if the user presses or holds down a keyboard key.
onkeyup	The JavaScript invoked if the onkeyup event occurs that is, if the user releases a keyboard key.
onmousedown	The JavaScript invoked if the onmousedown event occurs that is, if the user clicks a mouse button.
onmousemove	The JavaScript invoked if the onmousemove event occurs that is, if the user moves the mouse pointer.
onmouseout	The JavaScript invoked if the onmouseout event occurs that is, if the user moves the mouse pointer away from the text area.
onmouseover	The JavaScript invoked if the onmouseover event occurs that is, if the user moves the mouse pointer over the text area.
onmouseup	The JavaScript invoked if the onmouseup event occurs that is, if the user releases the mouse button.
onselect	The JavaScript invoked if the onselect event occurs that is, if the user selects text in the text area.
readonly	A Boolean value that specifies whether this text area should be rendered as read-only. If set to true, the text area value cannot be changed. If not selected, this value defaults to false.
rendered	A Boolean value that specifies whether the component is rendered on the page. If not specified, this value defaults to true.
required	A Boolean value that specifies whether this text area is a required field. If set to true, the user must specify a value for this text area. If not selected, this value defaults to false.
richText	A Boolean value that specifies whether this text area should save as rich text or plain text. If set to true, the value saves as rich text. If not selected, this value defaults to false.
rows	The height of the text area, as expressed by the number of rows that can display at a time.
style	The style used to display the text area component, used primarily for adding inline CSS styles.
styleClass	The style class used to display the text area component, used primarily to designate which CSS styles are applied when using an external CSS stylesheet.
tabindex	The order in which this text area is selected compared to other page components when a user presses the Tab key repeatedly. This value must be an integer between 0 and 32767, with component 0 being the first component that is selected when a user presses the Tab key.
title	The text to display as a tooltip when the user's mouse pointer hovers over this component.
value	A merge field that references the controller class variable that is associated with this text area. For example, if the name of the associated variable in the controller class is myLongDescription, use value="{!myLongDescription}" to reference the variable.

Visualforce Example:

<apex:page standardController="Contract">

<apex:form id="changeDescription">  

<apex:pageBlock >    

<p>Current description: {!contract.description}</p> 

<p>Change description to:</p>   

<apex:inputTextarea id="newDesc" value="{!contract.description}"/><p/>  

<apex:commandButton value="Save" action="{!save}"/>  

</apex:pageBlock> 

</apex:form> 

</apex:page>