# Custom fields

*Configuration*. Original contact attribute added to your email contacts. You can create up to 500 custom fields.

With custom fields, you can [segment your contacts][segment-contacts]. Segmentation lets you target email recipients based on the custom field values. Add custom fields for the use cases and user data that you need.

To label custom fields, you can use any label except those for [reserved fields][].

To learn how to add custom data, see [Using custom fields][].

[reserved fields]: /docs/sendgrid/glossary/reserved-fields

[Using custom fields]: /docs/sendgrid/ui/managing-contacts/custom-fields

[segment-contacts]: /docs/sendgrid/ui/managing-contacts/segmenting-your-contacts