# Introducing Transformations Transformations are used to perform a variety of operations on data as it moves through the dataflow pipeline. Astera Data Stack provides a full complement of built-in transformations enabling you to build sophisticated data maps. Astera Data Stack transformations are divided into two types— record-level and set-level. ### Record-level Transformations Record-level transformations are used to create derived values by applying a *Lookup*, *Function*, or *Expression* to fields from a single record. Examples of record-level transformations include *Lookups*, *Expressions*, and *Function* transformations. In Astera, data records flow between set transformations. Record-level transformations are used to transform or augment individual fields during these movements. A record-level transformation can be connected to only one set transformation. For instance, a *Lookup* or *Expression* cannot receive input from two different set transformations. ### Set-level Transformations Set-level transformations, on the other hand, operate on a group of records and may result in the Joining, Reordering, Eliminating, or aggregating of records. Examples of set transformations include *Join*, *Sort*, *Route*, *Distinct*, etc. *Data Sources* and *Destinations* are also considered set transformations. Other than transformations that enable combining multiple data sources—such as *Join*, *Merge*, and *Union*—transformations can receive input from only one set transformation. Transformations, however, can receive input from any number of record-level transformations as long as all these record-level transformations receive input from the same transformation. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://documentation.astera.com/astera-data-stack-v9/dataflows/transformations/introducing-transformations.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.