is_tag

The timeline below displays how wordpress function is_tag has changed across different WordPress versions. If a version is not listed, refer to the next available version below.

WordPress Version: 5.5

/**
 * Determines whether the query is for an existing tag archive page.
 *
 * If the $tag parameter is specified, this function will additionally
 * check if the query is for one of the tags specified.
 *
 * For more information on this and similar theme functions, check out
 * the {@link https://developer.wordpress.org/themes/basics/conditional-tags/
 * Conditional Tags} article in the Theme Developer Handbook.
 *
 * @since 2.3.0
 *
 * @global WP_Query $wp_query WordPress Query object.
 *
 * @param int|string|int[]|string[] $tag Optional. Tag ID, name, slug, or array of such
 *                                       to check against. Default empty.
 * @return bool Whether the query is for an existing tag archive page.
 */
function is_tag($tag = '')
{
    global $wp_query;
    if (!isset($wp_query)) {
        _doing_it_wrong(__FUNCTION__, __('Conditional query tags do not work before the query is run. Before then, they always return false.'), '3.1.0');
        return false;
    }
    return $wp_query->is_tag($tag);
}

WordPress Version: 5.4

/**
 * Determines whether the query is for an existing tag archive page.
 *
 * If the $tag parameter is specified, this function will additionally
 * check if the query is for one of the tags specified.
 *
 * For more information on this and similar theme functions, check out
 * the {@link https://developer.wordpress.org/themes/basics/conditional-tags/
 * Conditional Tags} article in the Theme Developer Handbook.
 *
 * @since 2.3.0
 *
 * @global WP_Query $wp_query WordPress Query object.
 *
 * @param int|string|int[]|string[] $tag Optional. Tag ID, name, slug, or array of such
 *                                       to check against. Default empty.
 * @return bool
 */
function is_tag($tag = '')
{
    global $wp_query;
    if (!isset($wp_query)) {
        _doing_it_wrong(__FUNCTION__, __('Conditional query tags do not work before the query is run. Before then, they always return false.'), '3.1.0');
        return false;
    }
    return $wp_query->is_tag($tag);
}

WordPress Version: 5.3

/**
 * Determines whether the query is for an existing tag archive page.
 *
 * If the $tag parameter is specified, this function will additionally
 * check if the query is for one of the tags specified.
 *
 * For more information on this and similar theme functions, check out
 * the {@link https://developer.wordpress.org/themes/basics/conditional-tags/
 * Conditional Tags} article in the Theme Developer Handbook.
 *
 * @since 2.3.0
 *
 * @global WP_Query $wp_query WordPress Query object.
 *
 * @param mixed $tag Optional. Tag ID, name, slug, or array of Tag IDs, names, and slugs.
 * @return bool
 */
function is_tag($tag = '')
{
    global $wp_query;
    if (!isset($wp_query)) {
        _doing_it_wrong(__FUNCTION__, __('Conditional query tags do not work before the query is run. Before then, they always return false.'), '3.1.0');
        return false;
    }
    return $wp_query->is_tag($tag);
}

WordPress Version: 5.1

/**
 * Determines whether the query is for an existing tag archive page.
 *
 * If the $tag parameter is specified, this function will additionally
 * check if the query is for one of the tags specified.
 *
 * For more information on this and similar theme functions, check out
 * the {@link https://developer.wordpress.org/themes/basics/conditional-tags/
 * Conditional Tags} article in the Theme Developer Handbook.
 *
 * @since 2.3.0
 *
 * @global WP_Query $wp_query Global WP_Query instance.
 *
 * @param mixed $tag Optional. Tag ID, name, slug, or array of Tag IDs, names, and slugs.
 * @return bool
 */
function is_tag($tag = '')
{
    global $wp_query;
    if (!isset($wp_query)) {
        _doing_it_wrong(__FUNCTION__, __('Conditional query tags do not work before the query is run. Before then, they always return false.'), '3.1.0');
        return false;
    }
    return $wp_query->is_tag($tag);
}

WordPress Version: 5.0

/**
 * Determines whether the query is for an existing tag archive page.
 *
 * If the $tag parameter is specified, this function will additionally
 * check if the query is for one of the tags specified.
 * 
 * For more information on this and similar theme functions, check out
 * the {@link https://developer.wordpress.org/themes/basics/conditional-tags/ 
 * Conditional Tags} article in the Theme Developer Handbook.
 *
 * @since 2.3.0
 *
 * @global WP_Query $wp_query Global WP_Query instance.
 *
 * @param mixed $tag Optional. Tag ID, name, slug, or array of Tag IDs, names, and slugs.
 * @return bool
 */
function is_tag($tag = '')
{
    global $wp_query;
    if (!isset($wp_query)) {
        _doing_it_wrong(__FUNCTION__, __('Conditional query tags do not work before the query is run. Before then, they always return false.'), '3.1.0');
        return false;
    }
    return $wp_query->is_tag($tag);
}

WordPress Version: 4.6

/**
 * Is the query for an existing tag archive page?
 *
 * If the $tag parameter is specified, this function will additionally
 * check if the query is for one of the tags specified.
 *
 * @since 2.3.0
 *
 * @global WP_Query $wp_query Global WP_Query instance.
 *
 * @param mixed $tag Optional. Tag ID, name, slug, or array of Tag IDs, names, and slugs.
 * @return bool
 */
function is_tag($tag = '')
{
    global $wp_query;
    if (!isset($wp_query)) {
        _doing_it_wrong(__FUNCTION__, __('Conditional query tags do not work before the query is run. Before then, they always return false.'), '3.1.0');
        return false;
    }
    return $wp_query->is_tag($tag);
}

WordPress Version: 4.4

/**
 * Is the query for an existing tag archive page?
 *
 * If the $tag parameter is specified, this function will additionally
 * check if the query is for one of the tags specified.
 *
 * @since 2.3.0
 *
 * @global WP_Query $wp_query Global WP_Query instance.
 *
 * @param mixed $tag Optional. Tag ID, name, slug, or array of Tag IDs, names, and slugs.
 * @return bool
 */
function is_tag($tag = '')
{
    global $wp_query;
    if (!isset($wp_query)) {
        _doing_it_wrong(__FUNCTION__, __('Conditional query tags do not work before the query is run. Before then, they always return false.'), '3.1');
        return false;
    }
    return $wp_query->is_tag($tag);
}

WordPress Version: 4.3

/**
 * Is the query for an existing tag archive page?
 *
 * If the $tag parameter is specified, this function will additionally
 * check if the query is for one of the tags specified.
 *
 * @since 2.3.0
 *
 * @global WP_Query $wp_query
 *
 * @param mixed $tag Optional. Tag ID, name, slug, or array of Tag IDs, names, and slugs.
 * @return bool
 */
function is_tag($tag = '')
{
    global $wp_query;
    if (!isset($wp_query)) {
        _doing_it_wrong(__FUNCTION__, __('Conditional query tags do not work before the query is run. Before then, they always return false.'), '3.1');
        return false;
    }
    return $wp_query->is_tag($tag);
}

WordPress Version: 3.7

/**
 * Is the query for an existing tag archive page?
 *
 * If the $tag parameter is specified, this function will additionally
 * check if the query is for one of the tags specified.
 *
 * @see WP_Query::is_tag()
 * @since 2.3.0
 * @uses $wp_query
 *
 * @param mixed $tag Optional. Tag ID, name, slug, or array of Tag IDs, names, and slugs.
 * @return bool
 */
function is_tag($tag = '')
{
    global $wp_query;
    if (!isset($wp_query)) {
        _doing_it_wrong(__FUNCTION__, __('Conditional query tags do not work before the query is run. Before then, they always return false.'), '3.1');
        return false;
    }
    return $wp_query->is_tag($tag);
}