In Splunk SOAR playbook development, the format block is used to assemble commands and data into a valid Splunk search query. This block allows users to structure and manipulate strings, dynamically inserting variables, and constructing the precise format needed for a search query. By using a format block, playbooks can integrate data from various sources and ensure that it is assembled correctly before passing it to subsequent actions, such as executing a Splunk search.

Other blocks, like action, filter, and prompt blocks, serve different purposes (e.g., running actions, filtering data, or prompting for user input), but the format block is specifically designed for building structured data or queries like Splunk searches.

Splunk SOAR Documentation: Playbook Blocks Overview.

Splunk SOAR Playbook Editor Guide: Using the Format Block.