# What is Talend Data Mapper?

Talend Data Mapper allows you to map complex data records and documents and execute transformations.

In the Mapping perspective of Talend Studio, you can create a map and configure it by simply dragging and dropping the data from an input structure to an output structure. For more complex mappings, you can create expressions, based on a set of functions, to define the value of an element. ![](https://help.qlik.com/talend/en-US/data-mapper-user-guide/8.0-R2025-02/Content/Resources/images/what_is_tdm_01_ui_overview.png)

Information noteNote: Talend Data Mapper is not shipped with Talend Studio by default. You need to install it using the Feature Manager. For more information, see [Installing features using the Feature Manager](https://help.qlik.com/talend/r/en-US/8.0/studio-user-guide/install-features-to-talend-studio).

## Core concepts

* A structure defines the semantics of the data. It contains a root and a hierarchy of elements. For more information, see [Working with structures](https://help.qlik.com/talend/en-US/data-mapper-user-guide/8.0/working-with-structures).
* A representation contains the information needed to produce a structure for a specific document format. The default representation is XML. For more information, see [Representations properties](https://help.qlik.com/talend/en-US/data-mapper-user-guide/8.0/representations-properties).
* An element is a portion of a structure, an XML element or a database column, for example.
* A map is a transformation between an input and an output structure. For more information, see [Working with maps](https://help.qlik.com/talend/en-US/data-mapper-user-guide/8.0/working-with-maps).
* A function is a unit of code that accepts a fixed or variable number of arguments and returns a single value. Functions are used to create expressions. For more information, see [Introduction to Talend Data Mapper functions](https://help.qlik.com/talend/en-US/data-mapper-functions-reference-guide/8.0).
* An expression refers to the use of one or several functions to define the value of an element. For more information, see [Standard map expressions](https://help.qlik.com/talend/en-US/data-mapper-user-guide/8.0/working-with-expressions).
* A loop is an expression that defines how to handle an element that can occur several times in the same object. For more information, see [Loop expressions](https://help.qlik.com/talend/en-US/data-mapper-user-guide/8.0/loop-expressions).