What does the term "theming" refer to in Liferay?

The term "theming" in Liferay specifically refers to the customization of the appearance of a portal. This process involves defining how the portal looks and feels to its users, which includes styling various components such as layouts, colors, fonts, and other visual elements. Theming is essential for creating a unique user experience and aligning the portal with an organization's branding.

Through the theming capabilities offered by Liferay, developers and designers can create and apply different themes to customize the visual aspects of the portal, ensuring that it reflects the desired aesthetics and usability requirements. This layer of customization enhances user engagement and satisfaction by making the portal visually appealing and user-friendly.

In contrast, the other options such as development of backend services, creation of database models, and implementation of security measures pertain to different functionalities within the Liferay platform that do not directly involve the look and feel of the user interface. Thus, these choices do not align with the definition of theming in Liferay.