Following are the hooks and functions which use to add custom meta boxes to one or more screens.

Hooks

• add_meta_boxes – Fires after all built-in meta boxes have been added.
• add_meta_boxes_{$post_type} – Fires after all built-in meta boxes have been added, contextually for the given post type.
• do_meta_boxes – Fires after meta boxes have been added
• add_meta_boxes_comment – Fires when comment-specific meta boxes are added.
• default_hidden_meta_boxes – Filters the default list of hidden meta boxes.

Functions

• add_meta_box() – Adds a meta box to one or more screens
• do_meta_boxes() – Meta-Box template function.
• get_hidden_meta_boxes() – Get Hidden Meta Boxes