Within the Design tab of many word processing applications (like Microsoft Word), you will find a group of commands dedicated to the visual appearance of your document. This group often includes options for themes, colors, fonts, and crucially, the background.
The specific button responsible for altering the document's background appearance is typically labeled as Background Styles.
Clicking this button reveals a gallery or dropdown menu of pre-defined background options.
These styles can range from simple solid colors to more complex gradient fills, textures, or even pattern fills.