A view is a virtual tables that is made up of one or more tables. It can be used for security purpose, hiding complex queries.
An Indexed view is a view that has unique clustered index created on it. This takes physical storage i.e it stores data. It will be used in OLAP, decision support where inserts/updates are low. It can be used in the following scenarios
1) Joins and aggregation of big tables.
2) Repeated joins of the same tables on the same keys.
Reference : Dilip Kumar Jena ( https://sqlexplore.wordpress.com )