Mainly there are two types of tranformation.1]Active TransformationAn active transformation can change the number of rows that pass through it from source to target i.e it eliminates rows that do not meet the condition in transformation.2]Passive TransformationA passive transformation does not change the number of rows that pass through it i.e it passes all rows through the transformation.Transformations can be Connected or UnConnected. Connected TransformationConnected transformation is connected to other transformations or directly to target table in the mapping.UnConnected TransformationAn unconnected transformation is not connected to other transformations in the mapping. It is called within another transformation, and returns a value to that transformation.list of Transformations available in Informatica:1 source qualifier Tranformation2..Expression Transformation 3..Filter Transformation 4..Joiner Transformation 5..Lookup Transformation 6..Normalizer Transformation 7..Rank Transformation 8..Router Transformation 9..Sequence Generator Transformation 10..Stored Procedure Transformation 11..Sorter Transformation 12..Update Strategy Transformation .13...Aggregator Transformation 14..XML Source Qualifier Transformation 15..Advanced External Procedure Transformation 16..External Transformation 16.. custom tranformationMostly use of particular tranformation depend upon the requirement.In our project we are mostly using source qualifier ,aggregator,joiner,look up tranformation