Each WordPress category may be provided with a description within the administration panel. Why a description is important for a WordPress category? The main benefit derived from using a description is mainly related to search engines and SEO optimization. If you specify a semantic markup structure, you can actually improve your site by adding more context to each category. Another benefit is for users: using a category description helps your readers to understand the topic you're writing about. Let's see how to use this feature in WordPress.
The function used to display a category's description is category_description():
<?php echo category_description( $category_id ); ?>
$category_id is the optional ID of the category you want to display the description. This function defaults to the current category when used inside category.php.
You can also use the category's slug:
<?php echo category_description( get_category_by_slug('category-slug')->term_id ); ?>
What's more, it's the HTML structure you'll choose that makes the difference from a SEO perspective:
<h1 class="cat-title"><?php single_cat_title();?></h1> <p class="cat-desc"><?php echo category_description();?></p>
A good combination is always heading + paragraph. Just remember to put your markup structure on top.