Data from two sources is combined by Lookup Transformation. There are matching fields from these sources. Case insensitive transformations is performed by the lookups. For the purpose of accessing additional information in relation to the tables is one of the purposes of lookups. Lookups can be used in data warehousing.

Lookups are used for the following purposes

► Data Cleansing

► Error Tolerance

► Data search in data warehouse

► Optimizations using cache modes