Span

The span type is created automatically by the rich text editor as part of the block type. It’s not something you will define yourself.

When you configure decorators and annotations for the rich editor, these will be stored as values in a span’s marks. Decorators as simple text strings, and annotations as keys that reference entries in the block’s mark definitions (markDefs). In the example below, there are marks in the third span with the values strong and cbe9d12c6af9. Most presentation layers will represent the strong as in a bold typeface. The other value is a key that corresponds to an object entry under markDefs that describes a link.

{
  "_key": "9d2d1ed68d84",
  "_type": "block",
  "children": [
    {
      "_type": "span",
      "marks": [],
      "text": "I am "
    },
    {
      "_type": "span",
      "marks": [
        "strong"
      ],
      "text": "strong and "
    },
    {
      "_type": "span",
      "marks": [
        "strong",
        "cbe9d12c6af9"
      ],
      "text": "annotated"
    },
    {
      "_type": "span",
      "marks": [],
      "text": ""
    }
  ],
  "markDefs": [
    {
      "_key": "cbe9d12c6af9",
      "_type": "link",
      "href": "https://www.google.com/?q=annotation"
    }
  ],
  "style": "normal"
}

Spans and Blocks are defined in the Portable Text specification for data storage. They provide insight into how a frontend might use the data provided. If you want to see how to render custom annotations and decorators, see this guide on Presenting Portable Text.