Which types of Expression Fragments can be authored in Adobe Journey Optimizer?

In Adobe Journey Optimizer, Expression Fragments can be authored in HTML and TEXT formats. HTML allows for the inclusion of structured content, such as links, images, and formatting, which enhances the visual appeal of messages. On the other hand, TEXT provides a straightforward way to present unformatted content, making it useful for simple messaging needs where no additional formatting is required.

Both formats serve distinct purposes, allowing for flexibility in how content is delivered to customers throughout their journey. This versatility is crucial for marketers who want to tailor messages depending on the context and audience.

The other options such as CSS and JSON may have their roles in web development and data formatting but are not recognized as valid formats for Expression Fragments within Adobe Journey Optimizer. Markdown is also not a supported format for Expression Fragments, as it is primarily used for formatting text in various scripting and documentation contexts, but not specifically within this platform's framework. Thus, the combination of HTML and TEXT captures the appropriate types of Expression Fragments that can be utilized effectively.