This type of relationship links two objects together. Lookup relationships are similar to master-detail relationships, except they do not support sharing or roll-up summary fields.
Salesforce objects include lookup fields that allow you to associate two records together in a relationship. For example, a contact record includes an Account lookup field that represents the relationship between the contact and its associated organization. The object that contains the lookup field is the source object, while the object the lookup points to is the target object.
With a lookup relationship, you can:
- Link two different objects.
- Link an object with itself (with the exception of the user object; see Hierarchical). For example, you might want to link a custom object called “Bug” with itself to show how two different bugs are related to the same problem.