# Conditional Logic
Surface Forms supports **conditional logic** to control how users move through your form. You can decide which step comes next, when to mark a response as completed, or when to stop users from continuing.
## Open the Logic Tab [#open-the-logic-tab]
1. Navigate to your form in the Surface editor.
2. At the top, click on the **Logic** tab.
3. Select the step you want to configure.
### 1. Change the Default Next Step [#1-change-the-default-next-step]
By default, each step flows to the next one in order. But you can change this:
1. Select a step (e.g., step0).
2. In the right-hand panel, open the **Default next step** dropdown.
3. Choose which step should follow.
This allows you to create **branching flows**, sending users to different paths depending on how your form is structured.
### 2. Mark a Step as a Completion Step [#2-mark-a-step-as-a-completion-step]
A **Completion Step** ends the form once the user reaches it.
* Toggle on **Completion Step** in the right-hand panel.
* When a user lands on this step, their response is marked as **Completed**, and workflows tied to completions will run.
Use this for your final **Thank You** or **Confirmation** screens.
### 3. Mark a Step as an Invalid Step [#3-mark-a-step-as-an-invalid-step]
An **Invalid Step** blocks the user from progressing further.
* Toggle on **Invalid Step** in the right-hand panel.
* When a user lands here, their response is marked as **Invalid**.
* Invalid responses will **not trigger workflows** and the user cannot move forward.
This is useful for:
* Filtering out unqualified leads
* Handling incorrect inputs
* Blocking progression when conditions aren't met
## Advanced Routing (Routing Rules) [#advanced-routing-routing-rules]
Advanced Routing lets you control how respondents move through your form based on their answers. Instead of a fixed linear flow, you can add logic to skip, branch, or redirect steps dynamically.
### What you can do with Advanced Routing [#what-you-can-do-with-advanced-routing]
1. **Add Conditions** – Define rules that check user inputs (e.g., email, company size, budget, etc.).
2. **Use Form Response Data** – Conditions can be applied directly on responses collected in previous steps.
3. **Customize User Paths** – Send users to different steps based on their answers.
### Example [#example]
Suppose you want to skip certain users directly to the end of the form based on their email address:
* **Condition**: If the email entered in **Step 0** equals [saharsh@withsurface.com](mailto:saharsh@withsurface.com)
* **Action**: Jump to **Step 2** (Thank you step)
* **Else**: Default path continues to **Step 1**
This way, you can create **personalized form experiences** depending on who is filling out the form.
You can combine multiple conditions using **AND** / **OR** logic to create powerful branching flows.