SalesForce-Difference between Master-Detail and Look-Up relationship

                                             

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Difference between Master-Detail and Look-Up relationship

 Master-Detail relationship :

  

1. It is a Strong Relationship.
2. If master record is deleted then all its associated detail records will get deleted.
3. Master-Detail relationship is created through a field on detail object and it is a mandatory/required field.
4. Security setting and  Look&Feel will be inherited from Master-Detail object.
5. RollUp summary fields are allowed.
6. Maximum 2 Master-Detail relationships per object. 

 Look-up relationship:
  

1. It is a weak relationship.
2. If parent record is deleted then all its associated child records may/ may not be deleted.
3. Look-Up relationship is created through a field on child object and it is an optional field.
4. Security settings and Look&Feel won't get inherited from parent to child object.
5. Rollup summary fields are not allowed.
6. Maximum 40 relationships per object [if we have used 2 relationships for Master-Detail then we can have maximum 38 relationship  Else we can use upto 40 Look-Up relationships]