A theme in WordPress is a collection of files that work together to produce a graphical interface with an underlying unifying design for web pages. These files are called template files and theme modifies the way the site is displayed, without changing the core files. It includes image files, customized template files, style sheets, custom Pages. etc

Themes are located in the Administration Screen > Appearance > Themes as additional selections.

BY Best Interview Question ON 02 Nov 2021