How can we add Regions in Drupal Theme and list some Default Regions?

Adding regions to a theme requires two things that's are given below :-

• Adding region meta-data to your THEMENAME.info.yml file.
• Please edit your page.html.twig file then print new regions.

Default Regions

• page.header
• page.primary_menu
• page.secondary_menu
• page.highlighted
• page.help (It has dynamic help text for admin pages)
• page.content (main content of current page)
• page.sidebar_first
• page.sidebar_second
• page.footer
• page.breadcrumb