apex:pageBlock

apex:pageblock represents an area of a page that uses styling similar to looks and feel of a Salesforce details page without any default content.

Example:

<apex:page standardController=”Account”>

    <apex:form >

        <apex:pageBlock title=”Account Details”>           

            <apex:pageBlockSection title=”My Content Section” columns=”2″>

                <apex:inputField value=”{!account.name}”/>

                <apex:inputField value=”{!account.AccountNumber}”/>

                <apex:inputField value=”{!account.type}”/>

                <apex:inputField value=”{!account.accountNumber}”/>

            </apex:pageBlockSection>                       

            <apex:pageBlockButtons >

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

            </apex:pageBlockButtons>

        </apex:pageBlock>

    </apex:form>

</apex:page>

here is the output of above page.

apex:PageBlock

apex:pageBlock attributes:

dir, helpTitle, helpUrl, id, lang, mode, onclick, ondblclick, onkeydown, onkeypress, onkeyup, onmousedown, onmousemove, onmouseout, onmouseover, onmouseup, rendered, tabStyle, title. 

Facets: footer, header

Refer this URL for more details about https://developer.salesforce.com/docs/atlas.en-us.pages.meta/pages/pages_compref_pageBlock.htm