Magento2: Display static block in Phtml file & CMS page.

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


in CMS Content:
{{block class="Magento\\Cms\\Block\\Block" block_id="block_identifier"}}


In Xml File:
<referenceContainer name="content">
  <block class="Magento\Cms\Block\Block" name="block_identifier">
<arguments>
<argument name="block_id" xsi:type="string">block_identifier</argument>
</arguments>
</block>
</referenceContainer>