In Wordpress administrator -> Configurations there is a tagline / description area:

For instance:

<div id="tagline"><p><?php bloginfo( 'description' ); ?></p></div>

description: I'm a <strong>web</strong> and graphic designer

However it appears enjoy it only enables text not HTMl tags.

Can there be in whatever way to do this o I must produce a new area?

The choice operates via a filter that replaces HTML organizations, so even when you had been to operate a filter on that option(that is possible), WordPress replaces the HTML organizations, meaning HTML wouldn't work...

For instance, add this code watching what goes on.

add_filter( 'option_blogdescription', 'html_blog_description' );
function html_blog_description( $option_value ) {
    $option_value = '<strong>Test text </strong>'. $option_value;
    return $option_value;
}

There isn't any hooks i can tell that particularly cope with this method and convert the organizations, else i'd have ideas about unhooking that action in the description.

I believe the only real solution you actually have would be to run str_replace over your calls to fecth your blog description. This could mean upgrading all of your requires bloginfo( 'description' ) having a rountine that works string alternative around the content.

eg.

$description = str_replace(' web ','<strong> web </strong>',get_bloginfo('description'));
echo $description;

Sure it isn't ideal, however i can't presently visit a more elegant way(though i'd be at liberty for somebody to prove me wrong).

You can just change it out inside your stylesheet.

#tagline {font-weight: bold;}