# Add types to parameters and headers with an API collection

You can add types to [parameters](/docs/sending-requests/create-requests/parameters/) and [headers](/docs/sending-requests/create-requests/headers/#configure-request-headers). Types can include data type, format, default value, and possible values. You can also specify if a component is required. Details you add will appear in the [collection's documentation](/docs/design-apis/collections/view-properties-and-documentation/#view-documentation-for-a-collection-with-types).

To add types to a parameter or header, do the following:

1. Open a request and click the **Params** or **Headers** tab. Add any [parameters](/docs/sending-requests/create-requests/parameters/) or [headers](/docs/sending-requests/create-requests/headers/#configure-request-headers) as needed.

2. Hover over a query or path parameter or a header and click <img alt="Manage icon" src="https://assets.postman.com/postman-docs/aether-icons/descriptive-manage-stroke.svg#icon" width="16px" /> **Type**.

   ![Add types](https://assets.postman.com/postman-docs/v11/type-definition-add-properties-v11-59.jpg)

3. Specify details for the parameter or header:

   * **Type** - Select the component's data type (string, integer, number, or boolean).
   * **Required** - Turn on if the component is required, or turn off if it's optional.
   * **Deprecated** - Turn on if the component is deprecated. A deprecated parameter or header is still functional, but its usage is discouraged because support may be discontinued.
   * **Default value** - Specify the default value for the component.
   * **Possible enum values** - (All data types except boolean) Enter the allowed values for the component (enumerations), and press **Return** or **Enter** after each item. You can also paste in a comma-separated list, such as "red,green,blue", and Postman adds each value.

   <img alt="Define types for a component" src="https://assets.postman.com/postman-docs/v11/type-definition-define-properties-v11-59.jpg" width="280px" />

4. Specify optional details depending on the component type:

   * Type **string**:

     * **Format** - Select the data format for the string (for example, date, time, or email).
     * **Pattern** - Enter allowed data patterns for the component using regex (regular expressions). You can't enter a pattern if you selected a format for the string.
     * **Min length** - Enter the minimum length for the component.
     * **Max length** - Enter the maximum length for the component.

   * Type **integer** or **number**:

     * **Min value** - Enter the minimum value for the component.
     * **Max value** - Enter the maximum value for the component.

5. Click <img alt="Save icon" src="https://assets.postman.com/postman-docs/aether-icons/action-save-stroke.svg#icon" width="16px" /> **Save** to save the changes to your request.

<Info class="iconless-callout">
  If you [generated a specification](/docs/design-apis/collections/generate-specifications/#generate-openapi-specifications-from-a-collection) from a collection, make sure to [update the specification](/docs/design-apis/collections/generate-specifications/#keep-openapi-specifications-in-sync-with-a-collection) once you're done making changes.
</Info>