Post Formats is a theme feature introduced with Version 3.1. Post Formats can be used by a theme to customize its presentation of a post.
illustration, ilustración, sign painting, rotulación, retolació, creativity, lowbrow, artisan, barcelona, sketch, helmet, custom, kustom kulture,
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post-template-default,single,single-post,postid-254,single-format-quote,stockholm-core-1.0.3,select-theme-ver-5.0.7,ajax_updown_fade,page_not_loaded,vertical_menu_enabled,wpb-js-composer js-comp-ver-5.7,vc_responsive

— Post Formats is a theme feature introduced with Version 3.1. Post Formats can be used by a theme to customize its presentation of a post.

– more on WordPress.org: Post Formats