# Reserved fields

*Configuration*. Predefined and protected attributes provided for email contacts. These are another type of [custom field][custom fields].

In Marketing Campaigns, they include fields such as `email`, `first_name`, and `last_name`.

To learn more, [Reserved Fields][].

[Reserved Fields]: /docs/sendgrid/ui/managing-contacts/custom-fields#reserved-fields

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