Magento 2 add static block in layout

Magento 2 add static block to layout XML

<referenceContainer name="footer-container">
      <block class="Magento\Cms\Block\Block" name="footerstaticblock" after="-" >
        <arguments>
          <argument name="block_id" xsi:type="string">footerstaticblock</argument>
        </arguments>
      </block>
    </referenceContainer>

Magento 2 add static block to TEMPLATE

<?php echo $block->getLayout()->createBlock('Magento\Cms\Block\Block')->setBlockId('block_identifier')->toHtml();?>

Magento 2 add static block to CMS

{{block class="Magento\\Cms\\Block\\Block" block_id="block_identifier"}}