# Contacts and groups

Contacts save you retyping numbers. Groups let you send one message to many contacts at once, such as all staff, a class or a team.

## Contacts

A contact holds a person's name and mobile number. Once saved, you can pick the contact as a recipient instead of typing the number.

## Groups

A group is a named list of contacts. Sending to a group sends one message to each member. A contact can belong to more than one group.

Members whose numbers are on your [stop list](/docs/reference/opt-outs/) are skipped when you send, even if they're still in the group.

<!-- NEEDS CAPTURE: how contacts and groups are created, edited, imported and deleted in the Iflow portal; field names; any limit on group size. -->

## Keep your lists clean

- Remove people who have left or asked not to be contacted.
- Store numbers in full. A number that can't be matched to a country fails with **9102**, and an invalid number fails with **9007**. See [Status and error codes](/docs/reference/sms-status-codes/).
- Numbers on the bad number list fail with **9001**.

## Related

- [Sending from the web portal](/docs/sending/web-portal/)
- [Sending to a large list](/docs/sending/bulk-sending/)
- [Opt-outs and the stop list](/docs/reference/opt-outs/)

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Source: https://iflow.net/docs/sending/contacts-and-groups/