Define Object relationship overview in salesforce?

Hi Piyush,

Create relationships to link objects with each other, so that when your users view records, they can also see related data. For example, link a custom object called “Bugs” to cases to track product defects that are associated with customer cases.

You can define different types of relationships by creating custom relationship fields on an object. Different types of relationships between objects in Salesforce determine how they handle data deletion, sharing, and required fields in page layouts.

Master-detail: Closely links objects together such that the master record controls certain behaviors of the detail and subdetail record.

Many-to-many: You can use master-detail relationships to model many-to-many relationships between any two objects. A many-to-many relationship allows each record of one object to be linked to multiple records from another object and vice versa.

Lookup: Links two objects together. Lookup relationships are similar to master-detail relationships, except they do not support sharing or roll-up summary fields.

External lookup: An external lookup relationship links a child standard, custom, or external object to a parent external object. When you create an external lookup relationship field, the standard External ID field on the parent external object is matched against the values of the child’s external lookup relationship field. External object field values come from an external data source.

Indirect lookup: An indirect lookup relationship links a child external object to a parent standard or custom object. When you create an indirect lookup relationship field on an external object, you specify the parent object field and the child object field to match and associate records in the relationship. Specifically, you select a custom unique, external ID field on the parent object to match against the child’s indirect lookup relationship field, whose values come from an external data source.

Hierarchical: A special lookup relationship available for only the user object. It lets users use a lookup field to associate one user with another that does not directly or indirectly refer to itself. For example, you can create a custom hierarchical relationship field to store each user's direct manager.