What happens when two or more plugins use the same hook?

There is priority as explained in the codex:

add_filter ( 'hook_name', 'your_filter', [priority], [accepted_args] );

Lower numbers are executed first, the default is 10.

If you have multiple functions at the same priority, they are run in the order in which they were added to the filter.

Related Posts:

  1. Difference Between Filter and Action Hooks?
  2. How many times will this code run? (or, how rich is grandma?)
  3. add_action hook for completely new post?
  4. WordPress Hook for user register
  5. Using filters and actions for plugin API?
  6. Explanation of the “posts_join” and “posts_fields” filter hooks?
  7. How do you use the plugin boilerplate loader class to hook actions and filters?
  8. Is it possible to remove next-post / previous-post with out creating a custom template?
  9. Why does do_action pass a blank string as the first parameter if no $arg is set?
  10. How to add a link to WordPress Plugin install Listing
  11. How to ensure “the_content” filter runs only for the main displayed content?
  12. Call activation hook multiple times
  13. What’s the difference between hooks, filters and actions? [duplicate]
  14. Two-step login process – Is it possible?
  15. How to check if certain plugin exists and in expected version
  16. How can I hook into existing WordPress Bulk actions?
  17. Earliest WP Hook to Safely and Reliably Redirect
  18. Define a function outside a class and call the function using action or filter hook
  19. Is it possible to modify the media library admin screen?
  20. What function to hook for changes made in status and visibility of a post
  21. Can I differentiate between “Delete Post Permanently” and “Empty Trash” and do something for each accordingly?
  22. Synchronize Custom post type tags to WordPress default posts tags
  23. Order of Operation for these three hooks
  24. Modifying values with add_action to be sent to db
  25. unable to stop loop when using wp_insert_post with publish_post hook
  26. save_post hook not triggered in WP v3.6.1
  27. Hook into theme-switching later than `setup_theme`
  28. Is it possible to delay execution of shortcode output callback?
  29. Hook to get image filename when it is uploaded
  30. How to display a message about updates in the plugin list
  31. Why my database table not created on activation?
  32. How to delete an user including data from custom database tables
  33. Act on user meta updated, but only once
  34. Is there any way to allow a plugin to write over a previous version?
  35. Should action callbacks start with a verb?
  36. Execute Hook on the footer or header after activating a plugin
  37. How to call function at the bottom of post using plugin?
  38. What filter should I use to insert a button inside on Media>Add New
  39. best practice for query string values – get_query_var always empty for my value supplied in query string
  40. get_current_screen() return null
  41. how to add custom functionality after woocommerce place order button
  42. How to use a hook to override an update_post_meta call in a plugin?
  43. External Authentication, session_tokens not destroyed on logout
  44. Conditional hook based on the core function that is calling it
  45. correct way to call javascript into hook function
  46. How to filter the_content() & include content from template
  47. Prefixing plugin hooks (actions/filters) with a wrapper class or functions
  48. Send push when new post is published in a certain category
  49. Force HTTPS 301 redirect with hook
  50. use of do_action() without any functions attached
  51. How to get all queries’s results after they have executed?
  52. flush rewrite rules after plugin update?
  53. Odd map_meta_cap $args on post edit — sometimes integer, sometimes string
  54. How can I create a custom plugin that allows anonymous users to signup without registering?
  55. hook filter after the_content on a specific page
  56. ECHO Executing 4 Times In Head
  57. Bind a function with its own argument to show something dynamically after every content
  58. What’s the hook for filtering every texts of site?
  59. Inserted double quote when prepending to the_content
  60. Hook add_attachment error
  61. Associate multiple email addresses with the same user account, so they can log in with either
  62. Run command “composer install” when activating wordpress plugin
  63. Update variable value via add_filter
  64. Custom filter not working
  65. Shortcode conflicts
  66. hook update_option/updated_option empty $old_value and $value
  67. Configure WordPress to Generate Scheme-less Relative URLs
  68. How to find list of all functions bind to a particular hook from my plugin?
  69. Ajax +wordpress onClick link redirect to new page and create html content
  70. How to replace settings in WordPress plugin from a theme
  71. Can / should a widget plugin define its own Widget Area?
  72. Creating posts with links from a txt file
  73. apply_filters() and call_user_func() to define and call a function outside a class
  74. Getting Post ID at “stylesheet” and “template” hooks
  75. Problem in plugin debuging in wordpress
  76. WordPress Plugin Boilerplate – add actions and/or filters based on user’s role
  77. OOP development and hooks
  78. Plugin Development – Call to undefined function comment_exists()
  79. Add_action not calling callback function
  80. how to retrieve post_id under woocommerce_add_to_cart_validation hook?
  81. add_option_{$option} action hook not being called
  82. Function not working on any file other than the main plugin file
  83. Custom signature appears twice on page
  84. Multi hook deploiement
  85. Can I use a hook other than ‘init’ to handle form submissions?
  86. woocommerce single product page hook not working
  87. How can I set a dynamic value for post_updated_messages based on return value of post_updated?
  88. What is the use of wp_schedule_event hook?
  89. How do I replace title with my plugin?
  90. Looking for Hook that is fired after a plugin or wp upgrade is installed/updated
  91. How to parse without changing the characters case (lower and upper) in wordpress the_content?
  92. append code after the_content not working
  93. Woocommerce: block user removing cart item
  94. echo statement repeats
  95. Insert plugin html content to a specific spot in the frontpage
  96. How can I get a plugin to hook ‘dbdelta_queries’ — a filter used during version update?
  97. Send retrieve password notification email with custom HTML email template
  98. get_term_by() returning null on plugin
  99. wp_head is not fired from the hook I have used in my plugin
  100. Trigger a JavaScript function based on the data fetched from Woo commerce hook