---
title: "Key concepts - Cloud"
canonical: "https://support.appfire.com/space/CSOT/68748484/Key%20concepts%20-%20Cloud"
format: markdown
---
> Macro (aura-html)

This page provides key concepts of the app, such as workflow post functions, issue fields, the definition of original and parent values, and so on.

## Workflow post function

As a Jira Administrator, you can control post functions, which are used to carry out additional processing that may be required after a workflow transition has been executed.

For example:

- Create a change history record for the issue.
- Add a comment to an issue.
- Update a field in an issue.
- Create an event to trigger one or more email notifications.

Jira has both [essential](https://confluence.atlassian.com/adminjiracloud/advanced-workflow-configuration-776636620.html#Advancedworkflowconfiguration-essentialpostfunctionsEssentialpostfunctions) and [optional](https://confluence.atlassian.com/adminjiracloud/advanced-workflow-configuration-776636620.html#Advancedworkflowconfiguration-optionalpostfunctionsOptionalpostfunctions) post functions and it is important that you understand their differences as they pertain to the introduction of new post functions with Create on Transition.

## Validators

Validators check that any input made to the transition is valid before the transition is performed. Input can include information gathered from the user on the transition's screen. If a validator fails, the issue does not progress to the destination status of the transition, and the transition's post functions are not executed. 

## Conditions

Conditions control whether the user can execute a transition. If a condition fails, the user will not be able to execute the transition. For example, the user will not see the transition button on the *View issue* page, and so will not be able to execute the transition.

## Issue fields

Create Issue, Update Issue, and Create Subtask post functions support a number of fields (Issue fields) that can be configured to help you control:

- When the issue should be created and
- What information is associated with the issue once created.

It is recommended to review each [issue field](https://appfire.atlassian.net/l/cp/Ypd71eza) and capability before creating the first post function.

## Original and parent values

**Original issue**: The original issue that started the workflow transition. This could be an issue or sub-task.

**Parent issue:** The parent issue of the original issue. If the original issue is not a sub-task, the parent is the same as the original.