You update a customer's information on their contact record. Then you notice the same information was copied onto three deals, and two of those copies are already out of date.
Repeated data creates repeated maintenance. It also leaves the team wondering which version to trust.
Ariyel Lookup fields display information through an existing contact–deal relationship. The source record owns the value, and the lookup makes it visible where your team also needs it.
Give the information one home
Suppose you keep a customer's preferred communication method in a custom contact field. Your sales team also wants to see it when working on that customer's deal.
You could create another ordinary field on the deal and copy the answer across. But when the preference changes, someone would have to remember to update both places.
Instead, add a Lookup on Deals that reads the preferred communication method from the linked contact. The deal displays the contact's value without becoming another place to edit it.
The same idea applies when a contact-level detail needs to be visible across several opportunities. Your team can work from the deal while keeping the underlying information on the customer record.
Choose the relationship and source
An owner or admin can create a field under Settings → Objects → Fields. Select Lookup, then choose the Relationship and Source field.
The relationship tells Ariyel which linked records to read. The source field tells it which piece of information to display. Give the lookup a name that makes its origin clear, such as “Contact communication preference.”
Check the existing contact–deal link as part of the setup. A lookup follows that relationship; it does not search your workspace for a similar name or infer which customer you meant.
Understand the direction
On a deal, a Lookup shows the linked contact's value. On a contact, a Lookup can show values from every linked deal.
For example, if a contact has several engagements, a contact-side lookup of the deals' service-type field can display the service values across those linked opportunities. Review that result with the relationship in mind: the contact can have more than one deal.
The feature is useful for viewing related information. Displaying deal values together does not, by itself, make the field a revenue total or a forecast. Use a clearly configured report when the question needs a calculation.
Edit at the source
Lookup values are read-only. When the communication preference changes, open the contact and edit the original field. The lookup reflects that source information.
This gives the team a clear maintenance rule. If a displayed value looks wrong, check the linked record and its source field instead of trying to overwrite the lookup.
Create a new Lookup rather than converting an existing ordinary field into one. Lookups currently work through contact–deal relationships, are not available for Tasks, and cannot use another Lookup or a Button field as their source.
Keep the dependencies clear
A lookup depends on its source. Remove dependent lookups before deleting the source field. Saved or default filters that use a lookup must also be removed before changing its source or deleting it.
Deleting the lookup removes the display field, not the values on the source records. That distinction makes it easier to reason about where your information actually lives.
Start with one piece of information your team keeps copying. Set up the relationship, add the lookup, and review it on a few records. The Custom fields documentation covers the setup and dependencies; our custom fields article helps you decide where the original information belongs.