Hi,

No worries, just simple.. Normally, when we use pageblock or pageblocksection,for the field value you are using like <apex:inputField> you can directly get your field label along with the field type, and also alignments will be like standard page layout. But, If you specify any field value with <apex:inputtext> you won't get the field alignment properly and also wont get the field label.

But, by using PageblockSectionItem, you can use the input/output text tags with proper alignment. For Example, first inputtext is mentioned in pageblocksectionItem is followed by 2 columns alignments if specified.

If you want to feel the difference, then try the below examples.

Try page without pageblocksectionItem,

<apex:page standardController="Account">
    <apex:form>
        <apex:pageBlock title="My Content" mode="edit">
            <apex:pageBlockButtons>
                <apex:commandButton action="{!save}" value="Save"/>
            </apex:pageBlockButtons>

            <apex:pageBlockSection title="My Content Section" columns="2">
              
                    <apex:outputLabel value="Account Name" for="account__name"/>
                    <apex:inputText value="{!account.name}" id="account__name"/>
             
                    <apex:outputLabel value="Account Site" for="account__site"/>
                    <apex:inputText value="{!account.site}" id="account__site"/>
            
        </apex:pageBlock>
    </apex:form>
</apex:page>

Try Page with pageblocksectionItem,

<apex:page standardController="Account">
    <apex:form>
        <apex:pageBlock title="My Content" mode="edit">
            <apex:pageBlockButtons>
                <apex:commandButton action="{!save}" value="Save"/>
            </apex:pageBlockButtons>
            <apex:pageBlockSection title="My Content Section" columns="2">
               <apex:pageBlockSectionItem>
                    <apex:outputLabel value="Account Name" for="account__name"/>
                    <apex:inputText value="{!account.name}" id="account__name"/>
                </apex:pageBlockSectionItem>

                <apex:pageBlockSectionItem>
                    <apex:outputLabel value="Account Site" for="account__site"/>
                    <apex:inputText value="{!account.site}" id="account__site"/>
                </apex:pageBlockSectionItem>
            </apex:pageBlockSection>
        </apex:pageBlock>
    </apex:form>
</apex:page>

Also, for your reference see the following link,

http://www.salesforce.com/us/developer/docs/pages/Content/pages_compref_pageBlockSectionItem.htm

Hope so this helps you...!

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