Here is the list with all the filters used used by default:
- store_single – filter on store description when information is for a single store
- stores_list – filter on store description in a list
- store_name – filter on store name when information is for a single store
- stores_name_list – filter on store name in a list
- item_single
- items_list
- item_name_single
- items_name_list
- page_single
- pages_list
- page_name_single
- pages_name_list
- product_single
- products_list
- product_name_single
- products_name_list
- category_single
- categories_list
- category_name_single
- categories_name_list
- review_single
- reviews_list
- user_name_single
- users_name_list
- admin_chat_message
- content – filter on widget text, it is the default filter for do_content() function
To understand how to add an action for one of these filters or for a custom filter you need to read: