This technical history is meant to provide a concise summary of what has changed in the codebase with a focus on code that affects how developers write WP core/themes/plugins/blocks. Please visit the posts linked to read more detailed explanations of these functions.

5.4

• What’s Coming in WordPress 5.4 (Features and Screenshots). wpbeginner, 2020.
• Jorge Costa. General Block Editor API Updates. wp make, 2020.
  • Meta attribute sources deprecated.
  • isMatch function for shortcode transforms.
  • New AsyncModeProvider API.
  • Add custom media uploader with a setting.
  • Easier drag-and-drop, removal of DropZone component.
  • RichText no longer sets focus when applying format.
  • New Guide component allows devs to easily add step-by-step guides for users.
  • wordpress/nux, DotTipe have been deprecated (use Guide instead).
• Jorge Costa. Markup and Style-Related Changes. wp make, 2020.
  • Legacy “editor-” class name compatibility has been removed.
  • Div with class “edit-post-layout__content” has been removed.
  • Removal of redundant wrappers on blocks and rich text components.
  • Simplified block margins (no mater built-in padding/negative margins for blocks).
• Jb Audras. New Hooks Let You Add Custom Fields to Menu Items. wp make, 2020.
• Riad Benguella. Fullscreen Mode Enabled by Default in the Editor. wp make, 2020.
• Jorge Costa. New Gradient Theme APIs. wp make, 2020.
• Garrett Hyder. Privacy Updates in 5.4. wpmake, 2020.
• Jb Audras. Miscellaneous Developer Focused Changes in WordPress 5.4. wp make, 2020.
• Jb Audras. WordPress 5.4 Introduces apply_shortcodes() as an Alias for do_shortcodes(). wp make, 2020.
• Jb Audras. Changes Related to Calendar Widget Markup in WordPress 5.4. wp make, 2020.
• Riad Benguella. An Updated Button Component in WordPress 5.4. wp make, 2020.
• Jb Audras. Formal Deprecation of Some Unused Customizer Classes in WordPress 5.4. wp make, 2020.
• Riad Benguella. Block Editor Keyboard Shortcuts in WordPress 5.4. wp make, 2020.
• Jb Audras. Enhancements to favicon Handling in WordPress 5.4. wp make, 2020.

5.3

• Matt Mullenweg. WordPress 5.3 “Kirk”. wordpress.org, 2019.
• Justin Tadlock. WordPress 5.3.1 Includes Security and Bug Fixes, Accessibility Enhancements, and Twenty Twenty Changes. wp tavern, 2019.
• Jeffrey Paul. WordPress 5.3 Field Guide. wp make, 2019.
• What’s New in WordPress 5.3 by Carlo Daniele. Kinsta, 2019.
  • A large number of improvements to Gutenberg including the addition of a Groups block that allows multiple blocks to be grouped together.
  • Addition of PHP register/unregister styles using register_block_style and unregister_block_style.
  • Added recovery_email_debug_info filter to ensure recovery emails include debugging info.
  • Added the site_status_test_result filter.
  • Added admin_email_check_interval filter.
  • Can now resume uploads, better image rotations using EXIF metadata.
  • Added Twenty Twenty theme.
  • Date/Time improvements including addition of wp_timezone_string(), wp_timezone(), wp_date(), current_datetime(), get_post_datetime(), get_post_timestamp().
    • Recommended to stop using date_i18n(), get_post_time(), current_time().
    • Added aria-current="page" attribute.
    • aria_label parameter added to _navigation_markup(), get_the_post_navigation(), get_the_posts_navigation(), et_the_posts_pagination(), get_the_comments_navigation(), get_the_comments_pagination(), the_post_navigation(), the_posts_navigation(), the_posts_pagination(), the_comments_navigation(), the_comments_pagination().
    • Support for rel="ugc" attribute in comments, added to new functions for adding nofollow and ugc values to rel attributes in links: wp_rel_callback(), wp_rel_ugc().
    • Improved REST API by adding support for 'array' and 'object' data types to register_meta() functions. Addition of fields parameter.
• Updates to Image Processing by Andrew Ozz. WordPress Make, 2019.
  • WP now saves meta data for image sizes before resizing the images.
  • WP now provides a refined largest image instead of actual largest uploaded as largest for use on site.
  • WP_Image_Editor_GD and WP_Image_Editor_Imagick have new methods make_subsize().
  • Addition of wp_get_missing_image_subsizes(), wp_update_image_subsizes(), wp_create_image_subsizes(), wp_get_original_image_path(), and big_image_size_threshold.
• Kristen Wright. WordPress 5.3 Overview: Top 20 New Features and Improvements. ithemes, 2019.
• Justin Ahinon. Introducing Handling of Big Images in WordPress 5.3. wordpress make, 2019.
• Justin Ahinon. Improvements in Media Component Accessibility in WordPress 5.3. wordpress make, 2019.
• K. Adam White. The REST API in WordPress 5.3. wordpress make, 2019.
• Jonny Harris. Enhancements to the Network Sites Screen in WordPress 5.3. wordpress make, 2019.
• Boone Gorges. Expanded Meta Key Comparison Operators in 5.3. wordpress make, 2019.
• Jb Audras. Use aria-label to Ensure Posts and Comments Navigation Has Proper Context in WordPress 5.3. wp make, 2019.
• Jb Audras. Changes to wp_die() HTML Output in WordPress 5.3. wp make, 2019.
• Jonathan Desrosiers. Miscellaneous Developer Focused Changes in 5.3. wp make, 2019.
• Jb Aubras. Noteworthy Admin CSS Changes in WordPress 5.3. wp make, 2019.
• Andrew Ozz. “Use of the “wp_update_attachment_metadata” filter as “upload is complete” hook.” wp make, 2019.
• Jb Audras. Integer Menu Slugs Are No Longer Supported From WordPress 5.3. wp make, 2019.
• Jb Audras. Core Widgets: New aria-current Attribute in WordPress 5.3. wp make, 2019.
• Andrey “Rarst” Savchenko. Date/Time Component Improvements in WordPress 5.3. wp make, 2019.
• K. Adam White. Filtering Nested REST Response _fields in WP 5.3. wp make, 2019.

5.2

• New Network and Sites Query Filters by William Earnhardt. WordPress Make, 11/2019.
  • On new short circuit filters to WP_Site_query (sites_pre_query) and WP_Network_Query (network_re_query).
• Jonathan Desrosiers. PHP Native JSON Extension Now Required. wordpress make, 2o19.
• Boone Gorges. Change to Post Globals Setup and Usage in get_the_content() and Related Functions in WordPress 5.2. wp make, 2019.
• Jonathan Desrosiers. Dashicons in WordPress 5.2. wp make, 2019.

5.1

• Andrea Fercia. New Styling for Admin Table Pagination Links in WordPress 5.1. wp make, 2019.
• Boone Gorges. Improved Taxonomy Metabox Sanitization in 5.1. wp make, 2019.
• Boone Gorges. LIKE Support for Meta Keys in 5.1. wp make, 2019.
• Adam Silverstein. New User Related Short Circuit Filters. wp make, 2019.
• Jonathan Desrosiers. New REST API Notice in 5.1. wp make, 2019.

5.0

• Pascal Birchler. New Post Type Labels in 5.0. wp make, 2018.
• Anthuny Burcell. Media 5.0. Guide. wp make, 2018.

4.7

• Helen Hou-Sandi. WordPress 4.7 “Vaughan”. WordPress News, 12/2016.
• Aaron Jorbin. WordPress 4.7 Field Guide. WordPress Make, 12/2016.
• Fred Meyer. Three This-Changes-Everything Features in WordPress 4.7. wpshout, 12/2016.
• Jeremy Felt. Multisite Focused Changes in 4.7. WordPress Make, 11/2016.
• Pascal Birchler. WP_Taxonomy in 4.7. WordPress Make, 10/2016.
• John Blackbourn. Fine Grained Capabilities For Taxonomy Terms in 4.7. WordPress Make, 10/2016.
• Andrew Ozz. Editor Changes in 4.7. WordPress Make, 10/2016.
• Registering Your Settings in WordPress 4.7 by Joe Hoyle. WordPress Make, 10/2016.
• Pascal Birchler. Post Type Templates in 4.7. WordPress Make, 11/2016.
• Boon Gorges. Comment “Allowed” Checks in WordPress 4.7. WordPress Make, 10/2016.
• Pascal Birchler. Attributes for Resource Hints in 4.7. WordPress Make, 11/2016.
• Pascal Birchler. New Post Types Labels in 4.7. WordPress Make, 11/2016.
• Felix Arntz. wp_list_sort() and WP_List in 4.7. WordPress Make, 11/2016.
• Eric Andrew Lewis. Using Custom Bulk Actions. WordPress Make, 10/2016.
  • One can now create custom bulk options to perform on lists within WordPress – e.g. posts, media, pages.
• Piotr Delawoski. Changes To Customizer Slider Panels/Sections in WordPress 4.7. WordPress Make, 9/2016.
• John Blackbourn. New Functions, Hooks, and Behaviour for Theme Developers in 4.7. WordPress Make, 9/2016.
• Gary Pendergast. WP_Hook: Next Generation Actions and Filters. WordPress Make, 9/2016.
• Aaron Jorbin. Global Overloading In advanced-cache.php. WordPress Make, 8/2016.
  • A change has been reverted relating to advanced-cache.php that was made in 4.6.

4.6

• Tom McFarlin. What’s New in WordPress 4.6. Tuts+, 8/2016.
• Matt Miklic. Native Fonts in 4.6. WordPress Make, 7/2016.
• Andrew Ozz. Editor Changes in 4.6. WordPress Make, 7/2016.
• Ryan McCue. HTTP API in 4.6. WordPress Make, 7/2016.
• Jeremy Felt. Enhancing register_meta() in 4.6. WordPress Make, 7/2016.
• Jeremy Felt. Additional register_meta() Changes in 4.6. WordPress Make, 7/2016.
• Rachel Baker. Comments in 4.6 Can Now Be Cached By a Persistent Object Cache. WordPress Make, 7/2016.
• Dominik Schilling. WP_Post_Type in 4.6. WordPress Make, 7/2016.
• Pascal Birchler. Shiny Updates in 4.6. WordPress Make, 7/2016.
• Pascal Birchler. Resource Hints in 4.6. WordPress Make, 7/2016.
• Boone Gorges. WP_Term_Query in WordPress 4.6. WordPress Make, 7/2016.
• Pascal Birchler. I18N Improvements in 4.6. WordPress Make, 7/2016.
• Weston Ruter. Pre-instantiated Widget Registration in 4.6. WordPress Make, 7/2016.
• Nick Halsey. Customizer Changes in 4.6. WordPress Make, 7/2016.
• And more…

4.5

• Aaron Jorb. WordPress 4.5 Field Guide. WordPress Make, 3/2016.
• And more…

4.4

• Pascal Birchler. New Embed Features in WordPress 4.4. WordPress Make, 2015.
• Ryan McCue. REST API: Welcome the Infrastructure to Core. WordPress Make, 2015.
• Joe McGill. Responsive Images in WordPress 4.4. WordPress Make, 2015.
• Konstantin Obenland. Document Title in 4.4. WordPress Make, 2015.
• Boone Gorges. 4.4 Taxonomy Roundup. WordPress Make, 2015.
  • This is a significant change, which affects home-grown taxonomy implementations.
  • Adds add_, update_, delete_, get_, etc. for term_meta, e.g., get_term_meta.
• Tammie Lister. Under the Hood of Twenty Sixteen. WordPress Make, 2015.
• Andrea Fercia. Headings Hierarchy Changes in the Admin Screens. WordPress Make, 2015.
• Jeremy Felt. Multisite Focused Changes in 4.4. WordPress Make, 2015.
• Aaron Jorbin. Changes to Fields Output by comment_form in WordPress 4.4. WordPress Make, 2015.
• Rachel Baker. Comment Object and Query Features in 4.4. WordPress Make, 2015.