$query = new WP_Query( array(
    'post_type'      => 'post',
    'posts_per_page' => 10,
    'category_name'  => 'news',
) );

if ( $query->have_posts() ) {
    while ( $query->have_posts() ) {
        $query->the_post();
        the_title();
        the_content();
    }
    wp_reset_postdata();
}

// Single post by ID
'p' => 42

// Multiple specific posts
'post__in' => array( 1, 2, 3 )

// Exclude posts
'post__not_in' => array( 10, 20 )

// By slug
'name' => 'hello-world'

// By page path
'pagename' => 'about/team'

// Multiple slugs
'post_name__in' => array( 'hello', 'world' )

// Multiple post types
'post_type' => array( 'post', 'page', 'product' )

// Multiple statuses
'post_status' => array( 'publish', 'private' )

// 10 posts per page, page 2
'posts_per_page' => 10,
'paged' => 2

// Skip first 5 posts
'offset' => 5

// All posts, no pagination
'posts_per_page' => -1
// or
'nopaging' => true

// By category ID
'cat' => 5

// Multiple categories (OR)
'cat' => '2,6,17'

// Exclude category
'cat' => '-12'

// By slug
'category_name' => 'news'

// Posts in ALL categories
'category__and' => array( 2, 6 )

// Posts in ANY category (no children)
'category__in' => array( 2, 6 )

// Single tag
'tag' => 'bread'

// Multiple tags (OR)
'tag' => 'bread,butter'

// Multiple tags (AND)
'tag' => 'bread+butter'

// By tag IDs
'tag__in' => array( 37, 47 )

// All tags required
'tag__and' => array( 37, 47 )

'tax_query' => array(
    'relation' => 'AND', // 'AND' or 'OR' between clauses
    array(
        'taxonomy'         => 'genre',      // Taxonomy name
        'field'            => 'slug',       // 'term_id', 'slug', 'name', or 'term_taxonomy_id'
        'terms'            => array( 'action', 'comedy' ),
        'operator'         => 'IN',         // 'IN', 'NOT IN', 'AND', 'EXISTS', 'NOT EXISTS'
        'include_children' => true,         // Include children terms
    ),
    array(
        'taxonomy' => 'actor',
        'field'    => 'term_id',
        'terms'    => array( 103, 115 ),
    ),
)

// By author ID
'author' => 1

// Multiple authors
'author' => '1,2,3'

// Exclude author
'author' => '-1'

// By nicename
'author_name' => 'john-doe'

// Multiple authors
'author__in' => array( 1, 5, 12 )

// Posts from January 2023
'year' => 2023,
'monthnum' => 1

// Combined format
'm' => 202301

// Complex date query
'date_query' => array(
    array(
        'after'     => 'January 1st, 2023',
        'before'    => 'December 31st, 2023',
        'inclusive' => true,
    ),
)

// Posts with specific meta value
'meta_key'   => 'color',
'meta_value' => 'blue'

// Numeric comparison
'meta_key'     => 'price',
'meta_value'   => 100,
'meta_compare' => '>=',
'meta_type'    => 'NUMERIC'

'meta_query' => array(
    'relation' => 'AND',
    array(
        'key'     => 'color',
        'value'   => 'blue',
        'compare' => '=',
    ),
    'price_clause' => array(  // Named clause for ordering
        'key'     => 'price',
        'value'   => array( 20, 100 ),
        'type'    => 'NUMERIC',
        'compare' => 'BETWEEN',
    ),
),
'orderby' => 'price_clause' // Order by named clause

// Basic search
's' => 'hello world'

// Exclude terms (prefix with -)
's' => 'pillow -sofa'

// Search specific columns
's' => 'hello',
'search_columns' => array( 'post_title', 'post_excerpt' )

// Exact phrase
's' => 'hello world',
'sentence' => true

// Single orderby
'orderby' => 'title',
'order'   => 'ASC'

// Multiple orderby
'orderby' => array(
    'menu_order' => 'ASC',
    'title'      => 'ASC',
)

// Order by meta
'meta_key' => 'price',
'orderby'  => 'meta_value_num',
'order'    => 'ASC'

// Preserve post__in order
'post__in' => array( 5, 2, 8 ),
'orderby'  => 'post__in'

// Random with seed (for consistent pagination)
'orderby' => 'RAND(123)'

// Children of post 10
'post_parent' => 10

// Top-level pages only
'post_type'   => 'page',
'post_parent' => 0

// Children of multiple parents
'post_parent__in' => array( 10, 20 )

// Only password-protected posts
'has_password' => true

// Only non-protected posts
'has_password' => false

// Specific password
'post_password' => 'mypassword'

// Posts with comments open
'comment_status' => 'open'

// Posts with exact comment count
'comment_count' => 10

// Posts with more than 5 comments
'comment_count' => array(
    'value'   => 5,
    'compare' => '>'
)

// Only posts current user can read
'perm' => 'readable'

// Only images
'post_type'      => 'attachment',
'post_status'    => 'inherit',
'post_mime_type' => 'image'

// Specific types
'post_mime_type' => array( 'image/jpeg', 'image/png' )

// Optimized query (no extra queries)
'cache_results'          => true,
'update_post_meta_cache' => false, // Don't need meta
'update_post_term_cache' => false, // Don't need terms

// Return only IDs (fast)
'fields' => 'ids'

// Return ID => parent mapping
'fields' => 'id=>parent'

// Skip SQL_CALC_FOUND_ROWS (faster when not paginating)
'no_found_rows' => true

// Bypass all filters
'suppress_filters' => true

// Don't put stickies first
'ignore_sticky_posts' => true

public function __construct( string|array $query = '' )

public function query( string|array $query ): WP_Post[]|int[]

public function get_posts(): WP_Post[]|int[]

public function parse_query( string|array $query = '' ): void

public function have_posts(): bool

public function the_post(): void

public function rewind_posts(): void

public function next_post(): WP_Post

public function have_comments(): bool

public function the_comment(): void

public function rewind_comments(): void

public function get( string $query_var, mixed $default_value = '' ): mixed

public function set( string $query_var, mixed $value ): void

public function get_queried_object(): WP_Term|WP_Post_Type|WP_Post|WP_User|null

public function get_queried_object_id(): int

public function setup_postdata( WP_Post|object|int $post ): true

public function generate_postdata( WP_Post|object|int $post ): array|false

public function reset_postdata(): void

public function init(): void

public function fill_query_vars( array $query_vars ): array

public function parse_tax_query( array &$query_vars ): void

public function set_404(): void

$query = new WP_Query( array(
    'post_type'      => 'post',
    'posts_per_page' => 5,
    'meta_query'     => array(
        array(
            'key'     => '_thumbnail_id',
            'compare' => 'EXISTS',
        ),
    ),
) );

$query = new WP_Query( array(
    'post_type'  => 'product',
    'meta_query' => array(
        array(
            'key'     => '_price',
            'value'   => array( 10, 50 ),
            'type'    => 'NUMERIC',
            'compare' => 'BETWEEN',
        ),
    ),
    'orderby'    => 'meta_value_num',
    'meta_key'   => '_price',
    'order'      => 'ASC',
) );

$query = new WP_Query( array(
    'post_type' => 'post',
    'tax_query' => array(
        'relation' => 'AND',
        array(
            'taxonomy' => 'category',
            'field'    => 'slug',
            'terms'    => 'news',
        ),
        array(
            'taxonomy' => 'post_tag',
            'field'    => 'slug',
            'terms'    => array( 'featured', 'breaking' ),
            'operator' => 'IN',
        ),
    ),
) );

$query = new WP_Query( array(
    'post_type'  => 'event',
    'date_query' => array(
        array(
            'after'  => array(
                'year'  => 2023,
                'month' => 6,
            ),
            'before' => array(
                'year'  => 2023,
                'month' => 12,
                'day'   => 31,
            ),
            'inclusive' => true,
        ),
        array(
            'hour'    => 9,
            'compare' => '>=',
        ),
        array(
            'hour'    => 17,
            'compare' => '<=',
        ),
        'relation' => 'AND',
    ),
) );

$post_ids = new WP_Query( array(
    'post_type'              => 'post',
    'posts_per_page'         => 100,
    'fields'                 => 'ids',
    'no_found_rows'          => true,
    'update_post_meta_cache' => false,
    'update_post_term_cache' => false,
) );

// $post_ids->posts is array of integers