Final answer:
The default theme is the pre-selected theme applied to software or applications such as operating systems or content management systems like WordPress.
Step-by-step explanation:
The term default theme typically refers to the pre-selected theme that is applied to a program or software application when it is first installed or used. For example, most operating systems, like Windows or MacOS, come with a basic theme that dictates the appearance of the user interface, such as the colors, icons, and layout. In the context of content management systems like WordPress, the default theme is the basic template design that is active upon installation before any customization takes place.
In WordPress, the default theme changes with new annual releases. These themes are usually named after the year they are released. For example, as of my knowledge cutoff in early 2023, recent default themes include Twenty Twenty-One, Twenty Twenty, and Twenty Nineteen. It is important to note that default themes for other software or applications will vary and have different naming conventions.