Placeholders are symbolic expressions that are replaced with actual data at runtime. You can use placeholder in all workflow components that require data, for example in templates, programming, validation messages, etc. Every time you insert a placeholder using the standard Select Placeholder dialog box.
In most cases, the Select Placeholder dialog box has the Object Fields, System Macros, User Macros, and Workflow Parameters categories, as illustrated above. Depending on the task you are performing, there may be some additional categories, described below.