You can specify how the slice data appears in a web browser when exported with an HTML file. The available options vary according to the slice type you select.
Image slices contain image data. This is the default content type.
No Image slices let you create empty table cells that can be populated with text or a solid color. You can enter HTML text in a No Image slice. If you set the “Text is HTML” flag, the text is interpreted as HTML when viewed in a browser. Slices of type No Image aren’t exported as images and can be previewed in a browser.