Unique - this index helps to maintain the Data integrity by ensuring that there is no repetition in the two identical values. This reputation might be the data in a table or in any other database record. It maintains the value of index keys as unique.
Clustered index - clustered index records all of the physical values of the table and database which are entirely based on the key values. Over each table, there will be a single clustered index.
Non clustered index - this index does not alter the physical value from any segment. Each table under this can have a 999 non clustered indexes in a logical order.