Difference between unique constraint and unique index

[sanjay92]

Question : Doesnt a foreign key reference need a primary key to point at, and not a unique constraint. (even though primary key is a unique constraint also).
Ans:The foreign key could reference to Unique key as well as Primary key.

Question:Also will creating a unique constraint also automatically create a index.
Ans: Yes, it will create index.

Thanks
Sanjay