---
language: en
title: How to add hidden fields to forms
category: Flows
summary: Learn what hidden fields are, what they are used for and how to add them to a form flow to store extra booking information.
---

# How to add hidden fields to forms

We have added a new type of field to the custom fields of form flows. These are **hidden fields**, and you can add them when [creating a form flow](https://www.tucalendi.com/en/s/flows/how-to-create-flows-for-forms).

## What are hidden fields

Hidden fields are a type of **custom field** that you add to the form flow. They let you store information when your customers make a booking with you. **A hidden field is not visible to the person making the booking** from the widget or the booking page.

## What hidden fields are used for

Hidden fields are used to **identify information** about the people who make bookings, to work with the data and to **keep track of the information** related to each booking.

For example, you can add a hidden field to **track bookings** for an event you use in a certain **campaign**, or include a value without customers having to fill in the field.

Let's see how to add a hidden field to a form flow.

[Log in to TuCalendi](https://account.tucalendi.com/) with your username and password. In the side menu, click on **"Flows"**:

![Form flow menu](https://www.tucalendi.com/images/content/flows/en/flow-menu-four-types.png)

In the **"Forms"** option, click on **"Select"**:

![Form flow with events assigned](https://www.tucalendi.com/images/content/flows/en/form-flow-with-events.png)

A form flow appears because we have previously created it and assigned the events.

> [!WARNING]
> [If you have not created any form flow, the list will be empty and you must create it.](https://www.tucalendi.com/en/s/flows/how-to-create-flows-for-forms)

To add new fields to the form flow, click on **"Edit"** in the corresponding flow:

![](https://www.tucalendi.com/images/content/flows/en/edit-form-flow.png)

Click on **"Add custom field"** to open the menu with all available custom field options.

![Custom fields menu](https://www.tucalendi.com/images/content/flows/en/custom-fields-menu.png)

Select **"Hidden field"**:

![Add hidden field](https://www.tucalendi.com/images/content/flows/en/add-hidden-field.png)

You only need to enter the **"ID"** of the field and choose the **"Type"** of hidden field.

> [!TIP]
> If you have chosen **"Custom"** as the hidden field type, you must enter the **value** the field will have.

Once your field is ready, click **"Add"** and the fields you add will be displayed in the form flow:

![Form flow with hidden fields](https://www.tucalendi.com/images/content/flows/en/form-flow-with-hidden-fields.png)

In this example, we have added two hidden fields with **system information** (booking number and customer language) and one **custom field** with the value "Facebook".

When you have added all the fields, click on the **"Save"** button and the form with the hidden fields will be created.

> [!TIP]
> From now on, the information from the hidden fields will be included in the **details of the received bookings**.