From b2evolution manual

Display tagline of the blog. This tagline can be edited by the blog owner in the admin interface under 'Blog Settings > General > Tagline'.

[edit] Example

<?php
  $Blog->tagline( array(
           'before' => ' ',
           'after'  => ' ',
           'format' => 'htmlbody'
    ) );
?>

[edit] Parameters

[edit] Return value

This tag displays content only, it does not have a return value.