Wordpress Query Parameters Taxonomy Parameter

Simple Taxonomy Query:
Display posts tagged with bob, under people custom taxonomy:
$args = array(
    'post_type' => 'post',
    'tax_query' => array(
        array(
            'taxonomy' => 'people',
            'field'    => 'slug',
            'terms'    => 'bob',
        ),
    ),
);
$query = new WP_Query( $args );

Multiple Taxonomy Handling:
Display posts from several custom taxonomies:
$args = array(
    'post_type' => 'post',
    'tax_query' => array(
        'relation' => 'AND',
        array(
            'taxonomy' => 'movie_genre',
            'field'    => 'slug',
            'terms'    => array( 'action', 'comedy' ),
        ),
        array(
            'taxonomy' => 'actor',
            'field'    => 'term_id',
            'terms'    => array( 103, 115, 206 ),
            'operator' => 'NOT IN',
        ),
    ),
);
$query = new WP_Query( $args );

Display posts that are in the quotes category OR have the quote post format:
$args = array(
    'post_type' => 'post',
    'tax_query' => array(
        'relation' => 'OR',
        array(
            'taxonomy' => 'category',
            'field'    => 'slug',
            'terms'    => array( 'quotes' ),
        ),
        array(
            'taxonomy' => 'post_format',
            'field'    => 'slug',
            'terms'    => array( 'post-format-quote' ),
        ),
    ),
);
$query = new WP_Query( $args );

Nested Taxonomy Handling:
The 'tax_query' clauses can be nested, to create more complex queries. Example: Display posts that are in the quotes category OR both have the quote post format AND are in the wisdom category:
$args = array(
    'post_type' => 'post',
    'tax_query' => array(
        'relation' => 'OR',
        array(
            'taxonomy' => 'category',
            'field'    => 'slug',
            'terms'    => array( 'quotes' ),
        ),
        array(
                        'relation' => 'AND',
                        array(
                    'taxonomy' => 'post_format',
                    'field'    => 'slug',
                    'terms'    => array( 'post-format-quote' ),
                        ),
                        array(
                                'taxonomy' => 'category',
                                'field'    => 'slug',
                                'terms'    => array( 'wisdom' ),
                        ),
        ),
    ),
);
$query = new WP_Query( $args );